So I haven't posted here in a long time, but my E30 project car has been parked for a good long while because of life happenings. I've got some time and money to drive it home though. As a recap, I've replaced the CVs and drive shaft, rebuilt the engine with all new fresh bearings, rings, gaskets, and head studs, installed an MS3, 4-pintle injectors, and found a nice junkyard steering wheel that looks so much better than the one that was in the car when I got it.
Anyway, now that I'm shifting my tool hand back to the car, I'm looking at acquiring the ITBs that I've wanted since I got the car and started learning about all this stuff. But I have a problem. I put a rebuilt junkyard engine in it. Only after I had it rebuilt and installed did I realize that it was an engine out of... you guessed it... a 1988 325. When I pulled it, all I remember seeing was the 885 head casting and the 'i' intake manifold, so I thought "yep, that's the one." In attempting to get a tune on the MS3, it never did work right because I had no idea what my required fuel number should be. So it's entirely likely that it's a 2.7L, but there's still a good chance that it could be a 2.5L. Who knows, the junkyard car could have had a regular 2.5L M20 swapped in it. All the bearings and rings and gaskets would still fit too. I would use the "welding wire in the spark plug hole and measure it" trick, but we can't use that because we have angled spark plug holes and I'm worse at trigonometry than I am at using TunerStudio. I'm not super comfortable just yanking the head either.
So the crux of this post: to 40mm or to 42mm? I obviously want to get this right, since it's an $1,850 expense (thinking the RHD kit).
I suppose the best way to answer the question would be to know my engine displacement. Does anyone have any ideas about how to determine my piston stroke with no uncertainty and without removing the head? If I botch it up and end up putting 42mm ITBs on a 2.5L otherwise-stock engine, will it be an undriveable disaster?
My reasoning of it is that I want it to be driveable and fun with just the manifolds bolted on. And no harm can come from using a 40mm throttle on a 2.7L engine, except maybe 10%ish less power potential, which doesn't bother me. Where the reverse (putting a 42mm throttle on a 2.5L engine) sounds like it would yield an engine that's a boggy mess in the low end. There's the idea that I'd love a ported heads and a cam in the future too, but I'm not in the position to make that happen right now.
So here's the possibilities:
Anyway, now that I'm shifting my tool hand back to the car, I'm looking at acquiring the ITBs that I've wanted since I got the car and started learning about all this stuff. But I have a problem. I put a rebuilt junkyard engine in it. Only after I had it rebuilt and installed did I realize that it was an engine out of... you guessed it... a 1988 325. When I pulled it, all I remember seeing was the 885 head casting and the 'i' intake manifold, so I thought "yep, that's the one." In attempting to get a tune on the MS3, it never did work right because I had no idea what my required fuel number should be. So it's entirely likely that it's a 2.7L, but there's still a good chance that it could be a 2.5L. Who knows, the junkyard car could have had a regular 2.5L M20 swapped in it. All the bearings and rings and gaskets would still fit too. I would use the "welding wire in the spark plug hole and measure it" trick, but we can't use that because we have angled spark plug holes and I'm worse at trigonometry than I am at using TunerStudio. I'm not super comfortable just yanking the head either.
So the crux of this post: to 40mm or to 42mm? I obviously want to get this right, since it's an $1,850 expense (thinking the RHD kit).
I suppose the best way to answer the question would be to know my engine displacement. Does anyone have any ideas about how to determine my piston stroke with no uncertainty and without removing the head? If I botch it up and end up putting 42mm ITBs on a 2.5L otherwise-stock engine, will it be an undriveable disaster?
My reasoning of it is that I want it to be driveable and fun with just the manifolds bolted on. And no harm can come from using a 40mm throttle on a 2.7L engine, except maybe 10%ish less power potential, which doesn't bother me. Where the reverse (putting a 42mm throttle on a 2.5L engine) sounds like it would yield an engine that's a boggy mess in the low end. There's the idea that I'd love a ported heads and a cam in the future too, but I'm not in the position to make that happen right now.
So here's the possibilities:
- 40mm on 2.5L: good stuff.
- 40mm on 2.7L: good but could have been better.
- 42mm on 2.5L: F in the chat.
- 42mm on 2.7L: great stuff.
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