Building a Motor, how to figure out what you can do...

[RSTPerformance]

ok... I am trying to decide what to do. I toasted the motor at Mid Ohio and I have to decide to put in another junker (without cleaning it up with new rings or anything) and run another race or just throw in the towel this year and just build a real motor for next season. Time is my main issue this fall as I will be starting a new job in about 2 weeks and need to put 100% dedication into that rather than racing. One positive is that even if I throw in the towel, I will still be doing another race, the Last Chance Enduro in my brothers car, so I will get my fix, I think.

If I decide to build a motor, how does one go about doing it???

We have the restriction in the GCR that says we can not increase compression by more than .5. My understanding is that you can easily do this just by plaining the head?

What about .040 over pistons? If I have some made (they don't exist for our cars) will that effect CR? If so how does it effect it? Also how will the .040 pistons effect performance vs .020 or stock sized pistons.

When determining the allowance to not increase CR by more than .5 is that based on your modifications from the engines min specs or is that based on the manufacturers spec (as noted in the GCR where your vehicles classification is). How would I determine what my CR is before and after making any mods (during the planning stages with a pile of parts)? Is a stock motors CR generally less than the manufacturers # or is it possibly higher?

Besides planning the head, and putting in larger .040 pistons (obviosly new rings go with that), and reseating the valves for a tight fit, what else would you recomend to do for a "80%" build? What about a"90%" build or a 100% build?

Thanks for the input;

Raymond "Personaly I can't believe huge gains can be made legaly, and I want to put it to the test" Blethen

[Greg Amy]

Big, big subject here, my friend. Lots of details, lots of information. What you're asking for is roughly decades of engine-building experience...

But, to answer a few quick questions:

> If I decide to build a motor, how does one go about doing it???

Pay someone that knows what they're doing. Hey, you asked...

> My understanding is that you can easily do this just by plaining the head?

Maybe, depends on the engine. You have to keep the engine within service limits, and there's decisively a service limit on how much you can "deck" the block. Further, you have to make sure you don't run into any problems with piston extension and valve interference.

In other words, it's not as simple as "planing the head".

> If I have some [.040 over pistons] made...will that effect CR?

Maybe, depending on the piston design.

If all you did was make overbore pistons with no other changes, you WILL increase the compression. To counteract this, manufacturers of factory overbore pistons will move the piston pin "up" in the piston ever-so-slightly in order to keep the compression ratio the same. If you're having some built (hold on to your wallet) you can design them to suit your situation.

> ...how will the .040 pistons effect performance vs .020 or stock sized pistons.

No substitute for displacement...and you have a five-cylinder engine, meaning you'll increase the displacement 25% more than a comparable 4-cylinder...

> When determining the allowance to not increase CR by more than .5 is that based on your
> modifications from the engines min specs or is that based on the manufacturers spec (as noted
> in the GCR where your vehicles classification is).

It's whatever the manufacturer publishes, usually in the workshop manual. The GCR may or may not be correct on this, it's your responsibility to verify that and have the ITCS changed, if necessary.

Once determined, it is your responsibility to make sure the engine subsequent to modifications is no more than 1/2 point over that factory value.

> How would I determine what my CR is before and after making any mods...

Measure cylinder volume at BDC and divide it by volume at TDC. Don't forget to "cc" the head volume as well as the volume around the piston up to the top ring...

> Is a stock motors CR generally less than the manufacturers # or is it possibly higher?

Varies. Usually spot-on for any kind of stable production process. But, you never know until you measure it...

> ...what else would you recomend to do for a "80%" build?

Rebuild it with new stock parts.

> What about a"90%" build or a 100% build?

Pay someone that knows what they're doing.

Hey, you asked...

[RSTPerformance]

> How would I determine what my CR is before and after making any mods...

Measure cylinder volume at BDC and divide it by volume at TDC. Don't forget to "cc" the head volume as well as the volume around the piston up to the top ring...
[/b]


Greg-

Thanks for the reply... To measure the above, how in the world do you do this??? I have asked a million times but I still can't get it. Life would be easy if ieverything was flat but nothing is flat or easily measurable other than the diameter of the cylinder ;). Can a good engine shop measure this and what is a "normal" cost to do that?

If I do take the engine to a good machine shop do I bring the GCR in hand and just tell them to build it to the limit? How would I know what they did was legal?

What about port matching the intake/exaust? Do you get any real gains in IT trim?

Also on a side note has anyone actually had an experience in SCCA where someone did measure the CR on an IT car or any other class? How was it done at the track?

Thanks again, I know it is lots of long questions, but I bet thier are a lot out thier that are also wondering.

Raymond

[joeg]

Deck the Block a few Thou, clean-up cut on the head. Align hone the crank; polish the crank. New Pistons--if you cannot get 40 over, go with 20 over.

A nice port match; good valve job and the best balance job you can find.

Other than the port match and assembly work, all this is farmed out to a machine shop. So find a good one!

[Greg Amy]

> To measure [compression ratio], how in the world do you do this??? I have asked a million times but
> I still can't get it.

It's relatively easy for someone with the the right tools and understanding of the process. Those tools include flat clear plates, a Burette, a low-surface-tension oil, a bore gauge, and depth gauge (or calipers). You measure bore and stroke and you get the swept displacement; you use the other tools to measure the amount of oil displaced by the head and piston tops. Simple math after that, and...

> Can a good engine shop measure this and what is a "normal" cost to do that?

Absolutely they can, and it's about an hour's worth of work with the head off the car.

> If I do take the engine to a good machine shop do I bring the GCR in hand and just tell them to build
> it to the limit? How would I know what they did was legal?

Yes. That's why it's important to hire a trustworthy builder.

> What about port matching the intake/exaust? Do you get any real gains in IT trim?

Absolutely. The amount is dependent on how bad it is from the factory.

> Also on a side note has anyone actually had an experience in SCCA where someone did measure the
> CR on an IT car or any other class? How was it done at the track?

Yup, mine was done after the '06 ARRC, exactly as I described above.

Greg

[planet6racing]

Raymond:

If you are going to do this yourself (you should find someone to do this for you and do it right), go to the bookstore and get a book on high performance engine building. It doesn't really matter whether it is a V8 or Honduh engine book, the basics are all the same. It will explain how to CC the motor (with pictures, too), how to balance conn rods the right way (not just simply matching the weights of the overall rod), and so on.

[RSTPerformance]

Raymond:

If you are going to do this yourself (you should find someone to do this for you and do it right), go to the bookstore and get a book on high performance engine building. It doesn't really matter whether it is a V8 or Honduh engine book, the basics are all the same. It will explain how to CC the motor (with pictures, too), how to balance conn rods the right way (not just simply matching the weights of the overall rod), and so on.
[/b]


No no.... I have always built my own motors and had decent luck, however this sort of stuff I would just send out for someone else to do (as Greg suggested). I basically want a list of what I should do, or need to do to get the most out of the engine. I want to do as much homework as possible on my dime rather than their dime (I still don't want to spend more than $1,000 or so). I am sure that the engine builder would have suggestions, but in reality how many engine builders have built IT engines that limit what exactly you can do. How many engine builders will know what is more benefitial, .040 pistons or "decking" the head till it just about hits the pistons (within the limit of the rules, not the factory spec). I have no idea, but I do want to have some sort of understanding.

One thing I do need to do is figure out the measuring CR... I think it is one of those things I need to do once and I will be good. I am thinking we need to have an NER tech seminar at one of the upcoming races where an Audi motor is brought in to be measured. not only would it be a good test (education) for the tech inspectors, but also for the stewards as well as the competitors. - what are the thoughts? I have an old stock motor sitting on the floor that I would donate.

Raymond

[924Guy]

Seems to me that Shine Racing Service can't be too far from you - they seem to know their VW/Audis, and IT to boot... they're in Walpole, MA... I always said if I were a little closer and had the cash to spend on a pro-built motor, they'd likely get it. FWIW, it cost me nearly as much just to build my own anyway...

Some more thoughts... did you figure out what killed the old motor, and how long did it last??

[RSTPerformance]

Seems to me that Shine Racing Service can't be too far from you - they seem to know their VW/Audis, and IT to boot... they're in Walpole, MA... I always said if I were a little closer and had the cash to spend on a pro-built motor, they'd likely get it. FWIW, it cost me nearly as much just to build my own anyway...

Some more thoughts... did you figure out what killed the old motor, and how long did it last??
[/b]


I think this is the 4th season on the motor, never had an issue before that wasn't related to forgetting to put on the fan... It was/is basically stock. I did not have any guages on it as I had run out of funds to fix the broken ones :unsure: ... All I had was Oil Pressure which was good till I parked it. I do know that our cars need the fan on at all times inorder to cool, and I know the fan was working. Stephens car was running around 260* (to high) when drafting and I may have toasted it trying to pull drafts off of people, not sure. Generally when the car overheats it blows a line, in this case it didn't for some reason.

As for Shine Racing Services, Shine is great with a lot of knowledge (although Eli is gone). I would buy any off the shelf product from them, but not sure if I could afford them ($$$ or length of time) for building something like an engine. I would probably use a local machine/engine shop that we have some experience with located in NH (Top Secret Place ;) )

Certainly interesting that it cost you as much to do your own as to take it to a shop...

Raymond

On second thought... Maybe the issue!!! I havn't run a race with this car all season, so it was the first time out from winter. When prepping the little water that was left from the winter was orange (rusty) could this have a major effect on the cooling of the engine? I emptied the fluids and left the hoses disconected for the winter, then in the spring reconected the hoses and filled it with my special blend (water and slight bit of antifreeze), flushed out and it was still a bit rusty colored, but no flakes of rust to be found.

Raymond

[planet6racing]

Get the book, regardless. It will help.

I did mine half and half. The engine builder did the machining and balancing, I did the assembly and head work. With new rods, pistons, rings, seals, etc., it was well over $1000, and I ended up with a head that I do not know if I took off too much, too little, just right, etc. in the ports. Next head will be sent to him for flo-jetting.

Once the ecu rule passes (ha ha! I knew I could sneak that in there and not de-rail this thread! Oh, wait...), I plan to have a long, serious talk with my engine builder and his dyno (yes, his dyno can talk! Well, ok, maybe not. What do I know?).

[JeffYoung]

There is power in the bottom end (crank scraper, torque plate on "flexible" blocks, good seal with the rings, etc.) but I think most IT gains are made in the heads. The port matching is a big deal, at least on my motor, and improved flow on my heads by a documented 10%. Heads and exhaust are were you still see most improvement over stock; focus on that.

By the way, yes, you do see HUGE gains on some motors in IT trim. Mine is rated at 133 crank hp stock; I make 160 whp now with lots left to do. A good L24 Datsun (240z) motor will make 170 whp, with a 150 crank rating. See also Greg Amy's car for another example (150 whp IT, 140 crank stock).

In particular for 80s motors, I think just the attention to detail and "clean up" helps get power.

For what it is worth, I spent about $1500 on outside parts and services on my present motor. $900 for the head, and about $600 for bottom end parts. I assembled the bottom end with the help of a friend, and then put the heads on myself. I consider this to be about a 80% IT build. On a "V" motor, it's probably best to have the guy doing the port matching on the heads to install them on the block, etc.

[joeg]

Jeff--Do you mean honing[i] with a torque plate? I would not think you can add a plate to an open deck block under IT rules.

Finding a commercial honing torque plate for a 5 cyl. Audi would be a bit of a challenge. You could actually make one (or have one made) from an old cylinder head and a milling machine. Chop the head in half lengthwise and hog out the combustion chambers. I have also heard that simply stacking some good washers on a bolt for each head bolt hole in the block and torquing to spec actually imparts the same distortion for round honing purposes.

[JeffYoung]

Correct, I mean using a torque plate to make sure your honing of the cylinder bores is "true."

I've had at least one engine builder indicate that these things can be made using even just a head gasket as a pattern, for about $200 to $300.

[77ITA]

I do not have much to contribute to this discussion as I am not an expert engine builder, but I do have a few points that I would like to add.

To start with, I think we can agree that high performance engine building is a rather precise science. It's not outside any of our physical abilities, but there is not a lot of room for error and you must have the requisite tools and knowledge for the job. If you do not posses said tools and knowledge (and do not have the time/money/space to gain them), the job is better left to a professional; someone that has the ability to do the job correctly.

The above being said, I would like to provide a frame of reference. We all need trailers to go racing just like we need engines. I'm sure I could design and fabricate my own trailer, but I'm not willing / able to invest in doing so. Trailer manufacturing is a job best left to Haulmark and thus I 'paid someone else' to build my trailer.

[Ron Earp]

You'll want to use a torque plate and any decent machine shop can make you one. Steel piece thick enough to not distort, bored on your bore spacing and diameter, with holes for head bolts.

We farm our machine work out, assemble the motors, and then do the install. While not a super racey setup it doesn't cost a fortune and thus far has worked pretty well. Jeff's motor is pretty decent and will be stronger next go around, and I hope my Z motor turns out pretty good.

R

[Sandro]

how to determine your CR

http://www.valvoline.com/carcare/articlevi...g=pht20020701cr (http://www.valvoline.com/carcare/articleviewer.asp?pg=pht20020701cr)

this makes it easy to mess around with how much you need to take off to get where you want to be.

http://www.csgnetwork.com/compcalc.html

[tom91ita]

scca actually has a spreadsheet for CR:

http://www.scca.com/_FileLibrary/File/compratio.xls

tom

[RSTPerformance]

Thanks for all the reply's...

So do we have an ordered list of things to do for the best "bang for the buck" in order of most needed to least needed to get to a 100% build?

1- Pay someone if you don't have the right tools (possibly assemble yourself though)
2- New bearings and rings
3- Clean up the valve seats
4- Deck the head
5- Increase piston size
6- Port match
7- Balancing
8- New parts (what difference does it make beside prevent failure?)
9- Start the expensive stuff, such as balancing as well as flow testing?
10- Add the turbo or custom ecu ;)

Thanks for the additional comments, please fill in or move around the ist for me!!!

[Rabbit07]

Thanks for all the reply's...

So do we have an ordered list of things to do for the best "bang for the buck" in order of most needed to least needed to get to a 100% build?

1- Pay someone if you don't have the right tools (possibly assemble yourself though)
2- New bearings and rings
3- Clean up the valve seats
4- Deck the head
5- Increase piston size
6- Port match
7- Balancing
8- New parts (what difference does it make beside prevent failure?)
9- Start the expensive stuff, such as balancing as well as flow testing?
10- Add the turbo or custom ecu ;)

Thanks for the additional comments, please fill in or move around the ist for me!!!
[/b]

Don't Forget New Valve Springs! I also like new oil pumps and pick-up screens. Don't forget a good windage tray, my understanding is the Volvos get about 2 HP from oil control!

Be sure to properly break in the engine, One good intial heat cycle for the rings and springs before you put any load on it is also a good idea.

[gran racing]

What type of gains can typically be seen by adding a crank scraper?

[Ron Earp]

http://www.crank-scrapers.com/

I have one of these, but I have not installed it. Not sure it'll work with my NISMO pan which has some windage stuff built in as well as a rudimentary scraper.

If you read on that site and others it appears that folks can see a couple percent gain, although I'd expect that to be limited at some point. If you have a 1600 hp motor 3% would be 48 hp, but does the 1600 hp motor benefit from oil control that much more than a 200hp version? I guess what I'm trying to say is there should be a limit to how much hp you can gain with one of these in my opinion.

There are more than a few OEM cars that use them. Porsche has them in the bottom of a few pans, as does the big three on some engines, and in some Japanese cars as well. If they spend the money to do it then it is probably worthwhile.

Ron

[924Guy]

Good point on the valve springs; consider at least checking the valve guides for play as well, if not replacing outright. Rings... I've been very impressed with the effectiveness and longevity of my Total Seal rings. Crank scrapers... yes. I'm using an Ishihara-Johnson (crank-scrapers.com), went in nicely with a little tweaking, very cost-effective. No idea how much it gave me, though - was only a small part of the whole build. My stock pan is otherwise quite good, well baffled and finned.

I would definitely put balancing high on the list, even if limited - I've heard that it's pretty key for inline engines, especially the longer ones, like your 5's and 6's...

Sounds like you ought to consider uprating your cooling system. Many options here. Aftermarket, certainly; in my case, I had my rad re-cored with some kind of performance 3- or 4- row core by a local rad shop - I think the core was for some kind of Ford. It works GREAT - temps rarely go above halfway during full-race conditions in the worst heat - even worse than what we had at Mid-O.

That said, at least for the 924 motors (so very likely for yours, given the common heritage) keeping oil temps down is key to longevity. I run a massive oil cooler - have you any? Mine's the el-cheapo $50 or so 8x11.5" trans cooler sold by Racer Parts Wholesale. I also run a remote filter mount with a Rabbit Diesel MANN or Mahle oil filter (much better than the cheap Fram ones at filtering the smaller stuff). I also run a 3-qt Accusump; with my engine config (long. with a 45-degree layover) oil pressure can be hell on long LH-ers). I suspect you don't have the same kind of problem, or at least not as bad; the crank scraper also helps in this regard, fitting tightly by the low side of the block and providing some additional protection against oil creeping up the RH side of the block. This all also ups the system capacity to 2 gal! :D

BTW, when you say you blew the motor, what exactly was the failure? Loss of compression, headgasket, siezed, spun a bearing???

4 seasons on the motor - did you change the mains or rods in the process? I think my motor wants new rod bearings every other year, aiming to do mains as well this winter. Not sure about lifetime of the rings; they still register 98% or better (within noise of 100% IMO) on a leakdown... need to call my supplier, find out when I can tell I need to replace them...

Another longevity thing I've found, though perhaps your motors are better - my valve stem seals only last so long. Right now it seems to be only about half a season - say 4 weekends. Irritating. Thankfully I have the fancy VW/Audi tool to allow replacement of those with the head on (on-head valve spring compressor) - it's proved its worth, did them just before the IT-Fest. Keep an eye out for oily plugs. The high revs seem to shorten this; if I shift at redline (6500), they go quickly, as they just don't like the revs, whereas my normal 6000rpm shiftpoint may help extend the life. Not something you'll ever really see as an issue on a street car...

HTH...

[lateapex911]

And, I don't feel you can go into these things with an absolute set bufget, like $1000, unless you are accepting that you won't be getting what you want.

Find asecond job, get dreative in the money laundering world, whatever. Do it once, do it right, and don't screw with being cheap about things, especially like guages.

(And I'd leave antifreeze/water IN the engine over the winter, and oil too. )

[joeg]

Scrappers and windage trays do work. You have to be careful with the install to avoid oil leaks from the pan as well as checking where the oil pick-up lands up after adding such things.

Interesting comment about Total Seals. They are pricey, but frankly, the only reason I use them is thay can ship you any size you want so that you can file-to-fit--another DIY assembly trick.

BTW, bearings are normally not consumables--unless they were trashed. Obviously rings are as would be rod bolts. If you are rebuilding a motor with an unknown history, you should recondition the rods at the macjine shop to go along with an align hone of the main journals.

Anything you can find NOS on ebay for your motor helps too, such as an oil pump, rockers, cam shaft,etc.

[shwah]

We did a new motor over last winter. My original plan was 0.020 pistons, pay for machine work, assemble myself. We ended up with 0.040 pistons due to block condition. A freind with tons of engine assembly experience offered to help out, which I gratefully accepted.

I did not set a budget, but figured it would be about $1k, with my sponsor providing many of the hard parts free of charge. Well we ended up over $1400 for machine shop, but we used a race engine shop (AMT Racing Engines - St. Louis) for this and did not leave any items undone.

A good machine shop, that will use a torque plate is important.

I have always run a windage tray, so can't comment on gains. I have been thinking of trying a scraper though.

The balancing is more important than I expected. The motor spins so much more willingly now, regardless of how heavy stock parts and flywheel are.

We were running a 60k mile street engine (never even pulled the head on this one) before, that had a header, match port (yes I was dumb enough to do this with the head on the motor), correct fueling and timing. The gains were around 14% with the new motor, but peak did not tell the story. The power band drops much less in higher rpms. Peak torque gains were small, but the the curve has a plateau instead of a point at the peak and drops off much slower than before. I attribute these gains to good balancing, don't skimp here IMO.

[RSTPerformance]

We did a new motor over last winter. My original plan was 0.020 pistons, pay for machine work, assemble myself. We ended up with 0.040 pistons due to block condition. A freind with tons of engine assembly experience offered to help out, which I gratefully accepted.

I did not set a budget, but figured it would be about $1k, with my sponsor providing many of the hard parts free of charge. Well we ended up over $1400 for machine shop, but we used a race engine shop (AMT Racing Engines - St. Louis) for this and did not leave any items undone.

A good machine shop, that will use a torque plate is important.

I have always run a windage tray, so can't comment on gains. I have been thinking of trying a scraper though.

The balancing is more important than I expected. The motor spins so much more willingly now, regardless of how heavy stock parts and flywheel are.

We were running a 60k mile street engine (never even pulled the head on this one) before, that had a header, match port (yes I was dumb enough to do this with the head on the motor), correct fueling and timing. The gains were around 14% with the new motor, but peak did not tell the story. The power band drops much less in higher rpms. Peak torque gains were small, but the the curve has a plateau instead of a point at the peak and drops off much slower than before. I attribute these gains to good balancing, don't skimp here IMO.
[/b]

Chris, was it a noticable gain on the track as well?

Raymond

[gran racing]

I was watching the Rolex series the other evening and they did a piece how they've proven that Audi engines actually lose power with mild engine builds. The curve only turns around once the final pieces are assembled, but unfortunately those aren't allowed in an IT car. ;)

Ray, I thought you said Stephen did a more extensive engine build fairly recently?

[JeffYoung]

Ray, for me, the gains between the stock motor I ran in 2003 and the two "IT" motors I've run since then are night and day.

[shwah]

The gains were noticeable. In the past we had to get a perfect exit, and a good draft to stay in touch with some of the competition. This year we were able to run side by side down the straight and keep up fine. I would say we were in the lower middle of our pack on power, upper of the pack on handling last year. This year we are in the upper of the pack for power. The Volvo is still stronger, but I can stay in touch. We will find out this weekend at Road America if the Fiero still runs away as we exit T14 the way he did exiting T7 at Blackhawk last year :eclipsee_steering: .

[JeffYoung]

Ray, I just made an old Korean lady cry for a half hour at a deposition, so I'm tired of being a lawyer and going to spend 15 minutes of my day with your 1 through 10 ranking list. This is of course "biased" towards my experiences with my car, which is a sloppy, smogged out, low compression late 70s V8. Your mileage may vary, and probably will. But I am probably a bit in the same boat as you that I didn't want to just dial up a builder and have an engine made, I wanted to do as much of it as I could to learn.

So here goes, your top ten, with my rankings of importance (high, medium and low):

1- Pay someone if you don't have the right tools (possibly assemble yourself though)

HIGH. You have to do this otherwise you are itching for disaster. Have the block hot tanked, honed and line bored by a machine shop, at a minimum.

2- New bearings and rings

HIGH -- NO engine rebuild/refresh is serious without doing this. In fact, I would consider this an absolute minimum if I was taking the time to get the motor out of the car.

3- Clean up the valve seats

MEDIUM. Medium in that it is not essential for reliability, but as a part of a good working of the head (port matching, etc.) I would consider the overall work on the head to be HIGH.

4- Deck the head

MEDIUM. The extra compression helps, but it can cause alignment issues, in particular with your cam timing, that could be difficult to solve. I still think the head and exhaust work is more important, by far, than the .5 bump in compression you could get from decking the head.

5- Increase piston size

LOW. The added displacement from an over bore is minimal, or at least was on my motor. More important is to get the bottom end put together right, with good gaps on the rings to save compression, a hone with a torque plate and a good balance for revs.

6- Port match

HIGH. At least for me, I saw significant gains on the flow bench by doing this. Not only are you matching the gaskets, but since you can go in 1" you can clean up some bad early twists and turns in the manifold, and poor casting.

7- Balancing

HIGH. Motor will rev higher, run "smoother" and potentially cooler, and last longer due ot less friction.

8- New parts (what difference does it make beside prevent failure?)

VARIES. Depends on teh part. No need for new pistons or con rods all of the time, on the other hand my motor is notorious for wearing cam lobes so I get a new one for $100 plus lifters every rebuild.

9- Start the expensive stuff, such as balancing as well as flow testing?

HIGH. This small stuff is the "key" to a good IT build. A good IT build is an accumulation of small advantages, which is why it is expensive.

10- Add the turbo or custom ecu

HIGH. Seriously, that ECU is going to get you some gains I think.

[924Guy]

LOL... I'm pretty sure he was joking about the ECU - I don't think it has much more impact on his car than on mine (as in, no ECU - it's all CIS).

I would disagree about the valve seats - I'd put at least lapping the valves in as a HIGH, as I've seen plenty of motors that flat-out don't seal there... Bit of a waste to do all the other stuff and not seal the combustion chamber. Not sure that a performance valve job isn't also rather valuable, just like port-matching...

[Rabbit07]

LOL... I'm pretty sure he was joking about the ECU - I don't think it has much more impact on his car than on mine (as in, no ECU - it's all CIS).

I would disagree about the valve seats - I'd put at least lapping the valves in as a HIGH, as I've seen plenty of motors that flat-out don't seal there... Bit of a waste to do all the other stuff and not seal the combustion chamber. Not sure that a performance valve job isn't also rather valuable, just like port-matching...
[/b]

The Valve Job is everything!!! Valve angles have alot to do with how much power you can make. Especially when the valve is not fully open.

Just an example. I have been an ASE Certified Master Technician for over 10 yrs, so I have some experience and skill. I bring this up because I do most of the work other than machining myself. The last engine I did for the Neon cost me less than $2500. That was with a cylinder head that cost about $850.00.
Spend the $, make it right, you wont regret it. Most of the HP is in the head. For every full point in compression ratio you'll see about a 2% increase in power. Not much there in compression unless you go way up. Get the rings to seal, get the valves to close tight, balance the rotating assembly. Run the lightest crank pulley and clutch that you can legally.

or buy the junker until you can afford it.

[JeffYoung]

Guys, probably wasn't clear. I was trying to say that just doing ONE item in the head is a medium, if that is all you intend to do. You need to focus on the head and the exhaust in toto; that is a HIGH. That is where the biggest gains are.

On the ECU, didn't the tin man have a brain??? LOL.....kidding, I didn't realize the Audi had mechnical fuel injection.

[shwah]

If Audi motors are like VW motors, a .5 increase from 'spec' compression ratio is closer to a 1 or .8 increase. The VWs CR numbers measured lower than advertized during the era of Ray's car. So I would recommend taking a look at this.

The head work is important, but it is important the understand what can and cannot be done. The final result needs to match the shop manual specs - no multi angle valve jobs unless your shop manual specifies one. This does not mean you cannot make improvements over a bad factory job, or worn seats/valves, just that you have a smaller window to work in.

Engine build is definitely a place where it is easy to say "well if I'm doing this much, I might as well take the next step", and for good reason - you are not allowed to do much, so if you want an advantage you have to do it all. Say that half a dozen times and you are 50-100% over your original intended budget, but an IT motor is not a highly stressed peice. It should be a build it once proposition - maybe freshen it after 5 years (I am surprised to hear the 924 needs attention so much more often). I mean what we end up with are just really nice street motors. Keep pressures and temps where they belong and they should live long productive lives.

[924Guy]

It should be a build it once proposition - maybe freshen it after 5 years (I am surprised to hear the 924 needs attention so much more often).
[/b]

You may in fact be right; I just would hate to find out the hard way that I was pushing it too long! With the noted exception of the valve stem seals. Do VW's have the same problem? Can you guys get teflon ones? They shouldn't be all that different...

Very interesting to hear about the VW CR issues...

[Rabbit07]

Vaughan,

Does your car have some unusual valve train angles that cause the valve to rock in the guide? It is not normal to prematurely wear out guide seals unless there is excessive side loading of the valve.

[joeg]

Build it once? 5 year rebuilds?

Wow...must not run many events. I am lucky to get a season and a half...if that.

If you race a motor it wears out. Rings and bores wear; my cams wear over time. While certainly not on the level of tires or brakes, motors are consumables in a race car.

That is why it is always good to pick-up some mechanical skills and also abide by the philosophy..."a pair and a spare".

[924Guy]

Vaughan,

Does your car have some unusual valve train angles that cause the valve to rock in the guide? It is not normal to prematurely wear out guide seals unless there is excessive side loading of the valve.
[/b]

It's all stock, and good new parts - guides, valves, etc. I don't know if there are unusual angles, or what "unusual angles" would constitute, either. George (Mazuro) warned me of the valve stem seals after I brought him my first set of plugs that, unbeknownst to me, were fouled by dead stem seams. He recommended teflon ones, but sadly, though they're available for the 944, the 924 ones are larger and not interchangeable. :(

Oh, yeah - I typically run at least 6 weekends per season - yes, may be higher than most.

[JimW337]

It hasn't been asked yet, but any good books out there detailing the building of a "race" engine?

I've rebuilt a lot of stock engines (air cooled VW's and Porshe's) but that is pretty basic stuff. Check the tolerances and replace if out of spec.

Any recommendations or reviews of books?

Thanks,
Jim W.

[JeffYoung]

Jim, they are probably marque specific. I've got one for Rover V8s from the UK, I know Ron Earp has a NISMO book for his 260z. Do some google work and see what is out there for your motor.

Also, someone above said it and it is true. Different motors respond better and allow more improvement in different areas. Compression bump in my motor is a bitch because of the V design adn because I can't do it with the pistons. But, my heads are extremely poor castings and the head work I had done showed real gains. Other cars really benefit from careful exhaust work (RX7). Etc.

[joeg]

Books--Plenty.

Vogelin's "How to blueprint the small block Chevy"; Smokey Yunick's "Power Secrets", all the "How to Rebuild_(name your marque)", Bill Jenkin's Book on Chevies, etc., etc. are all good and relevant not withstanding the prejudice to SBC(s).

Any "Hot Rod" magazine or "Circle Track" racing mag that features some kind of engine build story are good resources. So is "Hot VW(s0".

Shop Manuals are simply a necessary tool.

How to tune and modify build "short blocks", "cylinder heads", " ignition systems", exhaust systems, etc. etc. are also good.

Go to a Barnes and Nobles and knock yourself out.

All stress the same thing--clean, crack test , balancing, cleanliness, assembly lube, cleanliness, taping bolt holes, cleanliness, necessary tools, etc.

Keep it clean!! All the rules applicable to a pro-built SBC, whether for drag racing or oval track racing, apply to our motors.

[Andy Bettencourt]

I would also try and learn more about your motor. Find out what mods will give you the biggest bang for your buck. Jeff's porting was huge for him, on a Miata it didn't do squat. ECU tuning not that important for some? HUGE on a Miata that runs crazy rich at high RPM.

Know your enemy, strike the weak spots first.

[Eric Parham]

You may in fact be right; I just would hate to find out the hard way that I was pushing it too long! With the noted exception of the valve stem seals. Do VW's have the same problem? Can you guys get teflon ones? They shouldn't be all that different...

Very interesting to hear about the VW CR issues...[/b]

I'd guess that VW, Porsche and Audi stem seals are all the same. For VW, yes, we can get Teflon (white), but I wouldn't recommend them since NO oil gets by to lube the guides. The black rubber ones simply can't take the heat in an IT engine (or many street engines for that matter). There are some reddish brown ones that come in some otherwise high-quality gasket sets -- they're better than the black but still not best IMHO (although I'll still use them in a pinch). The best bet is the Viton (usually green seals) -- they can take the heat but still lube the guides and last for years.

On the VW CR issues, there is some disagreement over certain specs. For IT, we usually have to follow the Bentley (factory authorized) shop manuals and add 0.5 to that. Some actual CRs were otherwise spec'ed 0.1 to 0.2 higher (and listed more correctly in other non-official manuals). In addition, there are apparent differences between engines originally built in different locations (perhaps they weren't all checking CR the same way). Some of those did often have lower compression by 0.1 to 0.2. I don't think that would apply to Audi, though, since the Audi engines were all built in the same place, AFAIK.

[924Guy]

Thanks for the info, Eric. Unfortunately, my headgasket sets all come with green ones, so presumably they are the Viton seals. Sounds like I'd better get w/ Childs over the winter and try to figure out why we keep shredding them... unless my installation method has been lousy (quite possible, takes a little technique, and I think I did a better job this time around)...

[RSTPerformance]

Thanks for all the help everyone... Holding off on racing my car again this season, so you will likely see a much improved engine department in the Audi next season (Watch our Dave!!!)... I Would have liked to go to ARRC but as you can probably see I havn't had much time with the new jobs and what not...

Still open to the idea of going to the ARRC with my brothers car/truck/and 2 car enclosed trailer IF someone wants to join in sharing the travel expenses...

Also we will be at the Last Chance Enduro at the Glen in a few weeks!!! Canover... bring it, you will love the track, and the competition!!!

Raymond

[gran racing]

Yeah, I know Ray. You Audi already equaled mine down the back straight without a full engine build, actually you pulled me considerably with your torque at first then I was able to catch up. Becareful not to go too fast or we might have to get you into ITA where you can be competitive. :unsure:

Btw, there's no "d" in my last name. (other post)

[924Guy]

Yeah, then you hit your top end and started blowing us all away!!!

[gran racing]

I don't know Vaughn, it seemed like your car and mine were very equal on the back straight. I was quite impressed with the power your car had. Then there was that BMW who was just blew me away on the straight.