2.3L Street Engine Build

Stretch32 · 02-19-2021, 06:00 PM

I'm looking to assemble an engine with slightly more power for a '71E hot rod build.

Many of the components are from the original E core engine with some added parts that were available. At the end of the day, I want an engine that's zippy in traffic and good for curvy mountain roads that also will have reliability and longevity (not planning to track or DE the engine). I'm looking for thoughts (good or bad) from the builders or anyone who has built a similar engine.

Basic plan:

'71E case (standard machine work done by Ollie's)
2.2 cylinders bored to 85mm (re-coated)
10.5:1 CR JE forged pistons (85mm)
Stock E rods rebuilt
Stock rockers reground
twin plug ignition (Supertec distributor w/ twin CDIs / coils)
911T heads rebuilt to "S" spec and twin plugged (ported to match MFI)
MFI induction with '71E pump and '69E TB / stacks bored to 37.5mm
DC30 cams
SSI heat exchangers
Sport muffler of some type

I was planning to use TB / stacks I bought a few months ago advertised as 2.2S parts but the casting numbers (which I wasn't smart on until after purchase) are for a 2.0E engine. Additionally, the TBs / stacks are bored to 37.5mm vice 36mm so they're also larger than stock S ports. I'm not sure if this presents a problem with the parts I plan to use or if I should track down some unmodified 2.2E/S TBs / stacks and sell the modified ones.

In the end, I'd really like to run MFI induction since I like the look and think they're a neat vintage system. It would also keep the engine more inline with the period race look I was planning to build the overall car to.

I was also planning to set CR around 10-10.25:1 for a bit more power but I'm not adverse to running a single plug ignition and 9.5:1 pistons instead.

I've got a few months before this all starts to come together but I was hoping to get parts ordered and ready so I can get started quickly once I'm ready.

Thanks in advance for any input

Stretch

BURN-BROS · 02-19-2021, 06:23 PM

You should be Mod S and Twinplug with that compression

Stretch32 · 02-24-2021, 06:10 AM

Sorry for the delay. Thanks for the reply.

I was planning to use one of your twin plug distributors if I went 10:1 or higher on the CR. I'm actually planning to set CR at 10.2-10.3:1 like Porsche did back in the day (10.3:1 is what I think they ran).

Can you elaborate on the cam choice of MOD Solex vice the DC30 cam with the higher compression? Will the MOD Solex still keep the power band around the same RPM as the DC30? My goal is to build an engine that basically makes its power about where a stock 2.2E engine would be and I'm planning to use the stock E crankshaft.

Thanks again.

BURN-BROS · 02-24-2021, 06:25 AM

Mod Solex is a DC30. You would need confirmation from Dougherty Cams, but I would be 9.5 with twinplug with that cam, and I would still be concerned about detonation. I reserve the DC30 to single plug and 9.0/1 or lower

I personally would stick with ModS /10.5 . You will have good midrange and a very nice top end. HP should peak 6500, possibly a little higher due to the port diameter increase.

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by Stretch32

Sorry for the delay. Thanks for the reply.
I was planning to use one of your twin plug distributors if I went 10:1 or higher on the CR. I'm actually planning to set CR at 10.2-10.3:1 like Porsche did back in the day (10.3:1 is what I think they ran).

Can you elaborate on the cam choice of MOD Solex vice the DC30 cam with the higher compression? Will the MOD Solex still keep the power band around the same RPM as the DC30? My goal is to build an engine that basically makes its power about where a stock 2.2E engine would be and I'm planning to use the stock E crankshaft.

Thanks again.

OK, just wait. In your original post you were suggesting your choice was the Supertec twin plug........what changed damn it?

Of course I'm just teasing......Aaron makes a great product.

cmcfaul · cmcfaul's Garage

Thanks Henry. Will my SW chip and associated Motronics FI support the larger displacement? Or would I need a new chip?

Chris

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by cmcfaul

Thanks Henry. Will my SW chip and associated Motronics FI support the larger displacement? Or would I need a new chip?

Chris

I'm not an expert on EFI by any measure but my understanding is: Chips are programed to a specific formula. IE: fuel quality, compression, cam, displacement, exhaust, etc.
In your case, I would build a formula that has a successful history, drive the car with the chip you have and if you find a deficiency, tune first, chip second.

Stretch32 · 12:14 PM

Re-attacking on this thread.

I've been mulling this engine for a bit now and have started to think (based on the driving I expect to do) that a high compression, twin plug engine is probably a bit overkill for what I need. I've been leaning more toward building an engine that's more "stock" (for lack of a better term) in nature and my new thought is still to go with 85mm P/Cs (since I need to bore / hone the E cylinders anyway) along with a lower compression ratio and single plug ignition.

What I'm now considering is basically a 2.2S engine (~2.3L displacement with the 85mm P/C) but with DC30 cams. I was planning to run either custom 9.8:1 pistons or the off-the-shelf 9.5:1 versions that JE offers. Besides the cams, the engine (including MFI induction I would buy) would basically be an S engine.

One other option I'd considered was the exact same engine as above but running a 70.4mm crank from a 2.4L engine. All other variables, including cams and compression (either 9.5 or 9.8) would be the same and I would modify / tune the MFI to suit the larger engine.

I know the 66mm crank would probably be more peaky and the 70.4mm would buy more torque. From the engine builders, what are your thoughts with regard to street-ablity and general twisty road driving on the two engines?

Thanks in advance for the help.

Stretch