Where to you locate an alternate engine?

[TomL]

I have a question that I don't see addressed in the ST rules and I don't recall having been discussed in the forum. If you install an alternate engine, where can it be located in the engine compartment? Other than the paragraph in STO regarding engine setbacks for certain engines, it's addressed in only one place that I see - the allowance for FWD engines in RWD cars to locate the long block anywhere in the engine compartment, plus allowing firewall modifications to clear accessories.

But for all other engine swaps - nothing at all. So, if I swap one RWD engine for another, where can I put it? I can see at least two interpretations - 1) The "Roffe corollary" version - if you can swap engines, you can bloody well swap engines, i.e., put it any where it will fit. All engine swaps allow this and the FWD-to-RWD language above is just an additional allowance to also modify the firewall to clear FWD-oriented accessories. 2) There's nothing allowing you to move the engine, so it has to be in the stock location. But with a non-stock engine, what is "stock location"? The two normal definitions of stock location relate to either number one plug location or bellhousing/engine interface location. But with a non stock engine and/or transmission, what do these mean? If you swap a six into a four cylinder only car or vice versa, the distance from no. 1 plug to interface is different (and on a four to straight six swap, by maybe six inches). Do you move the engine to keep stock trans location, move the trans to keep the no.1 plug location, or what? And once you add an aftermarket trans, then what?

I seem to recall that at one time there was language requiring "stock location", but it's not there now (if it ever was). My reading would go with the first interpretation, because the "stock location" reading would need to have a definition of "stock location" to make any sense, for the reasons noted. If stock location was intended, I assume that the rule writers would have addressed what stock location means for non-stock parts. But I know what trouble assuming will get you into.

The only problem I can see with the liberal reading is that it would allow engine swappers to move their engines back as far as possible, while cars with stock engine and trans have no basis in the rules for doing so, and thus couldn't move theirs back at all. On the other hand, the rules already specifically allow maximum setback for FWD-to-RWD engine swaps. Why should they be the only ones to get that advantage over all other engine swaps?

So could someone enlighten me as what the rules are intended to say?

[Greg Amy]

If you install an alternate engine, where can it be located in the engine compartment?

It's an item on the committee's agenda. Feel free to offer debate/discussions/suggestions here.

GA

[TomL]

Well, Ill put in a vote for allowing the same rule for all engine swaps as you have already allowed for FWD-to-RWD swaps, except maybe for the "modify the firewall" allowance. If you're going to allow "latitude" in engine swaps, as discussed in the Intent section, you have to include some specific parameters. Otherwise, it all comes down to each individual's opinion of what is reasonable.

With the large number of variations that are possible with the allowed engines, there is no way that a "stock location" based rule (however defined) is going to cover all the possible engine swaps, or at least not without resulting in some unworkable engine positioning (e.g., 4-to-straight 6 swaps, or vice versa). Allowing "anything that fits in the unmodified engine compartment" is easily defined and enforceable. Plus it give maximum flexibility for fitting unusual combinations. And since you've already allowed it for FWD-to-RWD swaps, I see no rational basis for not also allowing it for all engine swaps.

Since this would usually allow swapped engines to sit further back that than the location of the stock engine, the remaining issue is whether stock engines should also be allowed to take advantage of the "anywhere in the engine compartment" language. I have no opinion on that - it's a form of rules creep to allow it, but a disadvantage stock engines to not allow it.

In addition to the fore-aft location issue, what is the rule going to be on engine height? Same problem as with fore-aft - the presumption is stock height, but with engine swaps, what does that mean? Again, I don't see a good solution for engine swaps other than "whatever fits". However, I think that allowing free heights for stock engines could be a serious rule creep issue. With dry sumps allowed, and free engine height, it may effectively require (expensive) dry sumps solely for the purpose of reducing CG height. It depends on how much you could drop the engine due to bell housing clearance, but if you could drop your engine three inches by going to a dry sump, would you feel the need to do so?

[Z3_GoCar]

Excellant point Tom. Let me interject with my swapped motor experience. My alternate motor accomplishes two things, it gets me a better intake manifold that didn't come with the generation of motors in the Z3. Also, I get a smaller motor so we don't have to weigh over 3k lbs. My alternate motor has the same bosses and transmission as my current motor, so it sits in exactly the same spot as the stock motor, bolted to the original ZF transmission when that motor came with a weaker Getrag from the factory. If I were to swap in a four cylinder, I'd place the motor in the exact same spot the four cylinder motors sat in the four cylinder version, and it too could be bolted to a ZF transmission.

[Matt93SE]

In addition to the fore-aft location issue, what is the rule going to be on engine height? Same problem as with fore-aft - the presumption is stock height, but with engine swaps, what does that mean? Again, I don't see a good solution for engine swaps other than "whatever fits". However, I think that allowing free heights for stock engines could be a serious rule creep issue. With dry sumps allowed, and free engine height, it may effectively require (expensive) dry sumps solely for the purpose of reducing CG height. It depends on how much you could drop the engine due to bell housing clearance, but if you could drop your engine three inches by going to a dry sump, would you feel the need to do so?

I agree there's a conondrum here. how to put all these worms back into the can?

One thing to think about though is that we have to keep stock ring gear diameter. That's going to be the engine lowering limit for most any car I can think of, as my trans bellhousing is within an inch or so of the bottom of my oil pan.
Also, I can't drop the engine but maybe an inch without cutting the crossmember and removing/relocating the steering rack before the bottom of the block/crank weights start banging into stuff.

That may not be a problem in other cars, but it's certainly an issue in mine.

[Chip42]

this one one of the issues I raised in my omnibus letter a long while back (right around the time tGA joined the STAC). at the time, I don't think there was language allowing FWD wngine into RWD cars to be put "wherever" or however that language reads now, but there are some simple rules that would reign this mess in pretty easily.

1 - determine IF the intent of the rules allows (or should allow) for stock engines to be lowered, set back, or rotated about the crank centerline (especially applicable to FWD).

2 - require some specific measurements - 1:installed engine's stock angular orientation about the crank centerline (referencing Cyl #1 bore centerline vs vertical) and 2: for transverse applications: installed engine's crank/bellhousing interface plane position relative to vehicle centerline as delivered in the doner car.

3 - as the baseline, use stock or installed engine's angular orientation and stock bellhousing interface position from vehicle centerline, or the chassis' stock bellhousing plane for any installed engine (stock or swap) in longitudinal applications.

based on the answer to the above questions, set the limits/tolerances from stock. allow or disallow certain modifications, such as cross member modification / replecement as mentioned by Matt. this could make some chassis automatically better than others, so is worth considering with point 1. consider allowing transvere installations a greater angular orientation freedom in exhange for longitudinal setups getting a verical allowance as both will help driveline orientation.

pretty easy set of rules, just needs to be codified. cart's way ahead of the horse already.

[Greg Amy]

Some interesting thoughts, Chip. I'll have to go look up your old letter (you wouldn't know that number, would you?)

But as a scrutineer, I see a big hole in the logic: how do you determine "stock" location? Angular orientation? None of this is documented in the factory shop manuals. What's the chances of finding a stock example of whatever car you're inspecting at the time (and not risk it being a ringer brought in by the same team)? As a competitor, I'd have my $25 appeal form already pre-filled out the moment they start to do the "stock location" measurements. And I'm pretty sure the competitor would win.

I'm personally leaning toward the "within the engine compartment" or something along the same lines. The category already has a fairly large set of engine allowances, and something like that is far easier to scrutineer. But on the other hand, what could someone do such an open reg? Would anything they do be a significant change? If so, do we care? I'd really like to brainstorm the extremes of what could be done if given a big open hole like that to drive through.

Remember, any reg we create must be able to be objectively measured against a known standard, by person of reasonable - but not extreme - technical talent.

GA