Spec e30 engine questions

[BMW_TUNER]

So a friend is going to be fielding a spec car next year he has purchased a great car that has been run in spec but it was missing the engine. He came to me and asked if I would help him put together his engine. We are picking up a core and going from there. So any secrets you guys in the know are willing to share would be appreciated? Help?

[Bimmerman325i]

What's your budget?

[e30_325es]

I'd recommend a full stock rebuild.

[jlevie]

A maxed out Spec E30 engine will be an 020 overbore and the head will be milled to minimum spec. Pistons and rods will be balanced as will the complete rotating assembly, from the harmonic balancer through the clutch. Coated bearings on polished journals are better than plain bearings. The head needs new guides, and may need new exhaust valves. The cam needs to be blue-printed back to spec or you need to use a new cam. Use a new oil pump and pressure relief valve and an IJ crank scraper. Use new injectors or have them cleaned and flow tested (I like RC Engineering for that).

[kishg]

pretty much what jim said, you will need new pistons when you overbore obviously. I'd do new rockers/rocker shafts as well. a baffled pan like the paul poore one would be a nice addition also.

[XvillainousX]

Save your money and use a low mileage motor until you get your car sorted out.

My friend who races Spec dyno'd his car on the same dyno that all of the other Nor Cal Spec e30 dyno on. His engine is original and has 200k miles on iy. He made 151hp and 150tq. Ron Harness made 150hp and 154tq and BTM who built a fresh motor made 132hp but 154tq.. I have yet to see a true hp/tq difference between fresh rebuilds and old 200k motors. Just go to Spece30.com and look in Nor Cal and you'll find a thread of dyno plots. I think the motor that ValleyMotorWerk did for a customer made the most HP/TQ. I forget the numbers. Doesnt matter anyways. Donney Edwards beats everybody.

[jlevie]

The original 225k engine in my first Spec E30 only made 152hp. The replacement 130k engine made 154hp and the built engine that I have in the new car made 162hp (on a 100F) day. So if the build is done properly it will outperform a junkyard motor. That said, a fast driver in a car with a weak motor will still win. An 8-12hp is pretty insignificant at most tracks.

[BMW_TUNER]

That is great input my firend will be so happy that people where willing to share. As far as the coatings go I thought that bearing coatings where against the rules?

[jlevie]

That is a a gray area of the rules. 9.3.1.2.4 says that bearings may be replaced. 3.5 defines replaced as meaning an item that meets or exceed OEM specifications. I maintain that coated bearings fall under 3.5. There is no competitive advantage to coated bearings. But they will tolerate brief periods of marginal lubrication where plain bearings will scuff.

[BMW_TUNER]

10-4 thanks

[M-technik-3]

spec is budget, have fun out the first year then maybe go a bit nuttier.

[Dyno4mance]

Running a tighter valve clearance (8 thou instead of 10) on the intake I know have been used by several racers in the south east and has yielded good and proven results on the dyno.

[jlevie]

I don't think I'd try it on a well used head, but on a fresh head with an in-spec cam I use 0.006" for the intakes and 0.008" for the exhausts (cold).

[1craze30]

I believe balancing is also agains the rules iirc, but I may be wrong there

[SpecM]

I believe balancing is also agains the rules iirc, but I may be wrong there

you are, balancing is legal