ITA 240SX KA24 refresh

I now have three seasons of 6-7 weekends each on the motor in my car. It only had a couple weekends on it when I bought the car so most of the use has been by me over the past three seasons. I'm wondering when I should start considering a refresh of the motor. I'm hesitant to open it up since it's been so good to me up till now, but I figure at some point it needs to be done. This motor is a top build with the usual stuff done to it. Bob said he just got a new motor when he needed one, but I'd like to just refresh this one if that makes sense.

Here are my questions.

- How do you know when it's time for a refresh? Compression test? Dyno run? Butt-o-meter on the track? Some other way? I can live with a few less horsepower, but I don't want to be significantly down.

- What does a refresh constitute? I figure rings (does that imply honing as well?) and probably the piston and main bearings. Valve springs seem likely. What else? Some sort of head cleaning to clean the valves?

- What parts? More precisely, what manufacturer of parts. These are .040 pistons so does Nissan make rings? Do you want Nissan rings or some performance rings? What about bearings and the other pieces? I have no idea what's in the motor now, but whatever it is seems to last.

- Where to get it done? I'm likely going to farm this out to a shop. I'm in Atlanta so Sunbelt is an obvious choice, but I've heard that they can take a long time and the quality depends on who does the work. I also don't know how much experience they have with the KA24. I'd prefer to use somebody that knows the motor and a smaller shop so I know who is doing the work. Ken (or is it Kevin?) Muresan mentioned to me at the ARRC a couple years ago that he uses somebody up in NC, but I don't remember the shop. I'm willing to travel a couple hours if it's a good shop. Anybody got any recommendations?

Thanks for any info.

David

A "refresh" is not new pistons--that's a "rebuild".

For a refresh, you want to re-ring it (which obviously entails at least a ball hone to break the cylinder glaze), gasket set and possibly valve springs (after testing with a Rimac). You generally take it apart, clean it and carefully inspect everything. Have the valves done.

You can polish the crank--if it needs it--and replace bearings (not always necessary) as well as put in a new oil pump and water pump. Carefully check the cam and lifters for wear.

Reassemble.

The only shops I can speak of with a history of wokr on the KA24's is Rebello and Sunbelt. Sunbelt did the head in the KA that I used to race. The head is where the power is, so don't take any shortcuts there. Even for a refresh, I would change the valve springs, or at least the exhaust springs. (retainers and locks also) They take a real beating. It'll likely need rod bearings also. I've used both the Nissan rings, and the gapless style in the Nissan .040 over pistons. The size is common enough that you can find some performance ones if you desire.

As for when to do it, you're own your own there. Some will say if it ain't broke, don't fix it. Some will say that an ounce of prevention...... You get the idea. Ask yourself some questions that might point to refresh time. How's the oil pressure? Is it the same as when the engine was fresh? How's the power? Dyno sheets will help tell if the HP is falling off. Oil temps still the same? An increase in oil temp might indicate a bearing getting tight-or other clearance issues.

Agree with Jim. Just monitor the essentials -- oil temp, pressure, compression and horsepower. If they are remaining fairly constant, then I wouldn't touch it.

I'll add another "half step" you can do here as well -- take the head off and have it refreshed. New guides, seals, check the valves, etc. There is some thinking that a new or freshened head on a "seasoned" or run in block makes the most power.

Was the NC engine builder Sam Neave? Or Dennis Shaw? Both work on Nissan motors and both are top notch.

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I now have three seasons of 6-7 weekends each on the motor in my car. It only had a couple weekends on it when I bought the car so most of the use has been by me over the past three seasons. I'm wondering when I should start considering a refresh of the motor. I'm hesitant to open it up since it's been so good to me up till now, but I figure at some point it needs to be done. This motor is a top build with the usual stuff done to it. Bob said he just got a new motor when he needed one, but I'd like to just refresh this one if that makes sense.

Here are my questions.

- How do you know when it's time for a refresh? Compression test? Dyno run? Butt-o-meter on the track? Some other way? I can live with a few less horsepower, but I don't want to be significantly down.

- What does a refresh constitute? I figure rings (does that imply honing as well?) and probably the piston and main bearings. Valve springs seem likely. What else? Some sort of head cleaning to clean the valves?

- What parts? More precisely, what manufacturer of parts. These are .040 pistons so does Nissan make rings? Do you want Nissan rings or some performance rings? What about bearings and the other pieces? I have no idea what's in the motor now, but whatever it is seems to last.

- Where to get it done? I'm likely going to farm this out to a shop. I'm in Atlanta so Sunbelt is an obvious choice, but I've heard that they can take a long time and the quality depends on who does the work. I also don't know how much experience they have with the KA24. I'd prefer to use somebody that knows the motor and a smaller shop so I know who is doing the work. Ken (or is it Kevin?) Muresan mentioned to me at the ARRC a couple years ago that he uses somebody up in NC, but I don't remember the shop. I'm willing to travel a couple hours if it's a good shop. Anybody got any recommendations?

Thanks for any info.

David
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David, The head is not the only place there is HP but it is a very big part of it. Start with a cylinder leakdown to see where you are at. If the motor is already .040 then measure the bore very carefully because you can end up with an illegal engine just from wear. Based on history thats a lot of hours on the engine and a good freshen (rings bearings cylinderhead overhaul) will be a benefit in performance. Again just measure everything closely. If I were in your half of the country I would recommend me but I am not so Sunbelt would be my choice.

Make sure that you change the oil pump drive gear and spindle as well. If that jumps time due to wear, kiss the motor good-bye and there is really no warning when it does it. We are planning on changing ours every 4-5 weekends. As you really start to push the limits of the motor it becomes increasingly important!

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David, The head is not the only place there is HP but it is a very big part of it. Start with a cylinder leakdown to see where you are at. If the motor is already .040 then measure the bore very carefully because you can end up with an illegal engine just from wear. Based on history thats a lot of hours on the engine and a good freshen (rings bearings cylinderhead overhaul) will be a benefit in performance. Again just measure everything closely. If I were in your half of the country I would recommend me but I am not so Sunbelt would be my choice.
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What parts would you recommend? Nissan OEM or some performance brand? I'd rather go in knowing what I want to have put in versus the shop telling me what to use.

I could pull the head off myself and take it somewhere to be freshened. I just didn't want to get into pulling pistons, doing rings, honing, etc. involved in the bottom end. If that's necessary then I'm just going to take the whole thing somewhere.

I'll do a compression test and take it to a dyno to get some numbers. I want to have some existing numbers to compare to new numbers as well. I don't have the equipment for a full leak down, but maybe I can get that done when I do the dyno runs.

Jeff, do you have numbers for those guys you mentioned? I really don't recall if either of them were the ones I was told about, but I'll give them a call and see what they say.

I've got a couple other household projects to finish up before I start on the car so I'm just trying to gather as much info as possible at the moment.

Thanks.

David

David. here's the info I have:

1. Dennis Shaw. He's doing my FI motor, so I usually just go by to see him, but I think his phone and e-mail are: Raliegh N.C. phone # 919 272 4107, email [email protected]


If you can't get a hold of him, let me know. I'll get his phone number when I am over there this week. He's a bit backed up though. If you need something done in a few weeks, probably won't happen -- but a great guy, very knowledgeable. Big time IMSA road racer in the 70s/80s, member of the US Road Racing club, etc. -- was essentially a factory Mazda driver in the 80s. Ran a 24 hour race on a 2 car AMC Spirit team with Lynn St. James and James Brolin at the Ring.

2. Sam Neave - (336) 824-1605. 3637 Walker Store Road. Franklinville, NC 27248.

David:

You may want to give Sam Moore a call, I know he is doing the 240 motor for a friend in Fla. now.

Les Chaney
#33 FP Volvo

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David:

You may want to give Sam Moore a call, I know he is doing the 240 motor for a friend in Fla. now.

Les Chaney
#33 FP Volvo
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Do you have some contact info? I figure it can't hurt to talk to as many people as I can. Thanks.

David

Hey David, I'll trade you motors. I might actually start that process next month. ugg.

What are your leakdowns? 4% or less and you still have a race motor. Spend the money on tires.

Thanks for the offer Tristan, but think I'll pass. Sometimes more air is a bad thing. :) Hope you get it rebuilt in the not too distant future. How's the house coming?

David

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What are your leakdowns? 4% or less and you still have a race motor. Spend the money on tires.
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Don't know at this point. Sounds like a leak down and some dyno runs should be a good indicator as to the health of the motor. I'll try and get that setup in the next couple weeks.

David

Working on the last bathroom now. Hopefully will be done with the whole thing by end of January. Of course new furniture not counting, I should finally be freed up with money and time to fix everything. If you decide to rebuild the motor let me know, maybe we can bring them in together and get some group discount somewhere!

Side note: We're looking for a rebuildable S14 engine. If you're aware of any, lemme know... - GA

Greg:

Shoot Brandon an email. We have a later 240 motor in the garage right now, mostly torn down for a project we were going to do that fell through do to customer funding. Can't remember what year the motor is out of, but it might be what you are looking for.