Engine update : from 2.2 to 2.4 to 2.7RS

[farleyd]

Well, anyone has the right to change their mind. While scouting options to get more from my 2.2 - options were 2.4 crank/rods or short-stroke 2.5. After compiling parts that i could have easily - friends and others or already have, one suggested to go for a 2.7RS replica.

Here is what i have so far:
2.7 7R case (studs renewed)
2.7 Nykasil cylinders
2.4/2.7 crank/rods
2.2E top-end w/S-cams (heads will be ported to i36 e35)
- - -
Ill need pistons with 9.5:1 ratio.

1) Any pistons suggestions for that set-up?
2) Any potential worries apart freaking out doing this?
3) Also have E-cams, should i use them instead of S?

Many thanks.

[Chuck Moreland]

I think Mahle makes these with 90mm 9.5, also JE

[farleyd]

Id really like the opinion of Early_s_man on this. Where are you?

[A Quiet Boom]

E-cams would be more drivable on the street given their lower powerband but as engine size increases it becomes less of an issue. For example a 2.0 with S cams will be significantly more peaky and have a higher powerband than a 2.7 with S cams. It looks like all out power is what you're after and your willing to give up some streetability to get it. My vote for a 2.7 would have to be S cams, but definately E for anything smaller.

[Wayne 962]

Wait 30 days before you do anything - I have a chapter on this with about 60 pages of info and pics!

The 2.7RS motor ran 'S' cams...

I personally don't care for the original RS spec - I think that you need to improve on it by bumping up the compression with some custom-made JE pistons. The original RS motor had low compression (8.5:1)

Stock 2.7 engine with
- S cams
- MFI
- JE 9.5:1 or 10.1 (I know someone with a good set of these new)

Will get you more power than the 2.7RS. I'm pretty sure that you will be able to run the stock RS-spec MFI pump too. The stacks are the same as the 2.4S so they are still around (I might have some). Not sure about the t-bodies off the top of my head - I think they are the same too...

-Wayne

[CRH911S]

Go over to Rennlist and check out the 2.7RS spec engine being offered for sale. I have it on very good authority that these are race engines and do not perform well under 3500rpm. That pretty much rules out street use. Just my two cents.
Regards,
Clinton

[CamB]

I dunno about unstreetable.

I have a 3.2RS (lucky me ) - an S cammed 3.2 short stroke.

It is very civil. Very torquey (especially with 10.3:1 c/r). It does benefit from EFI though.

Basically the size of engine makes up for the peakiness of the cam - I still have plenty of torque.

However, I have only driven a few hundred miles and opn the last drive (to and from the tyre shop) a pair (twin plug) of plugs fouled and I needed a run down the motorway to fix. They may be too cold or I may be forced to get 2x MSD (no CDI at the moment).

[skinnerd]

I'm prejudiced, but go with the 2.7RS engine configuration. Hugely streetable even with S cams and incredibly great fun to drive. Mine puts a big grin on my face each and every time. I'm talking about a stock 8.5:1 with S cams, MFI, etc, etc. The great thing about 8.5:1 is that you can use any kind of fuel, even 87 octane. Plant your foot, and she'll do 13.8 sec 1/4 miles at 98 mph (rear wheel dyno of 208hp; closer to 235 at the flywheel). If you need more than that, then go build your race motor.

Just my 2 cents.

[Wayne 962]

CamB - Apples and oranges - you can't compare the 3.2 to the 2.7...

The 2.7RS is not that peaky - they must have other trick mods. It's not like the very early 2.0S motors - it is a good street engine...

-Wayne

[CRH911S]

The 2.7RS spec. is a race engine. I didn't mean to steer the debate in a different direction. If this is seriously what you really want then I say go for it.
Regards,
Clinton

I find my 2.7RS motor is perfect for street use.