Increasing CR on a 3.2...how big of a difference will it make?
 

I have the opportunity to do some motor work on my 3.2L. It already has webers, SSI and WebCam 20/21 and runs very well but I was thinking about installing some 10.5 CR JE pistons and a little wilder cam.

How big of a "seat of the pants" difference am I going to feel with this?

Will I be able to run on pump gas?

Will it be streetable? It is not a daily driver by any means but I want to be able to drive the thing.

Open to suggestions...

Thanks, Chris

I wouldn't do 10.5 unless you are going to twin plug. and incrementally not sure you would notice much between the webcam 20/21 and the 993 ss. I'd shoot an email to web cam or camgrinder.

10.5 is twin plug territory, as well as high grade gasoline. I imagine you would definately feel the increase in power, but changing the cams and therefore powerband would probably give a bigger seat-of-the-pants difference, even in the CR was helping more than it felt.

What are the specs on the 20/21, that's not nearly as radical as an early S or mod-S cam is it, or even Solex? With webers, SSI's, high comp and reasonble cams (i.e. not GE80) I would consider it still streetable. Depends what you think is streetable, i.e. user "Ted" has a streetable race car, but perhaps too race for some.

I think camgrinder has a specific grind for webers and SSI's on the 3.2 - pretty radical if I remember correctly.

looks like it is in an early car so no emissions; the real step up would be pistons with big valve pockets (either 9.5:1 or 10.5:1 with twin plug depending on budget) and either PMOs or TWM 3003 based efi, or maybe supertec big-bore MFI, along with camgrinder's "Mod S" cams or similar. That would be a big upgrade. I wouldn't take the motor apart for what you're talking about; C.R. doesn't make that much difference in HP on its own.

While I am certianly not an expert, and Camgrinder will have the most accurate info, You will be limited to how radical a cam you can use pretty much by the fact you are using the DME Motronic ignition. The cam's duration will have to be right in the 112-113 area, which is a lot different than the early S cams you mention.

Assuming the JE pistons have preclearanced valve pockets in the dome tops, the next step up would probably be the Factory 3.8L RSR Super Cup Cams. They are only slightly more radical than your current 20/21 grind. check the lift & Duration #'s very similar.

I am running the 20/21 grind and the Mahle Euro 10.3:1 P/C's as well as a Steve Wong Chip tuned for 93 octane. I blend 50/50 100 & 91 octane for an avg octane of 94.4. I didn't twin plug so this is the price I pay to play with my toy.

Anyway, that's my .02.... good luck and keep us posted on what you end up doing.

Since I am using webers, it sounds like I should go with the 9.5:1 if I do anything at all. Yes, it is in an early car so I don't have to do any emmissions.

Are we talking about 30-40hp doing all of this or not? If not, maybe I should just shed more weight and leave the motor alone for now.

Decisions, decisions.

What provoked this idea is that this motor already has the webcam 20/21 cams and I want to put those in another motor that I will be leaving the motronic on. So basically two motors...

1st one... more of a race motor - 3.2, webers, SSI, poss 9.5:1 pistons and wilder cams.

2nd one... Street/club motor - 3.2, DME motronic, webcam 20/21 cams, SSI, steve wong chip.

I probably dont have the funds for twin plug now but I will probably do the machine work so it can be fitted later.

Thanks for the input guy!!!

duh, I missed the fact that you already have webers. are they 46s?

In this case changing pistons is very worthwhile, either 9.5:1 JEs for single plug or 10.5:1 JEs or Mahle Sport for twin plug.

for twin plug, look at competition engineering's site for machine work costs, it's not all that much. Then, look at the coil pack type ignition systems, not an RSR distributor, it may be more affordable than you think. if you're handy with electronics and programming you could do a megasquirt with ford EDIS modules for the twin plug for a very fair price.

the big reason to change the pistons, though, is the valve clearance, since I'm assuming the motor has stock pistons you can't run an 'S' type cam with them.

Motor 1 will still be a really good street motor in a lighter car, with Mod S cams or similar (maybe GE/DR40?) SSIs will be on the small side, for that motor, though. However, this is definitely at least a 30-40hp upgrade if done right.

Motor 2 is a nice combination as well, different personality.

forgot to add: with the Motor 1 setup especially it would be pretty smart to upgrade the rod bolts to ARP since the motor will want to spin a bit more. I guess this can be done through the case with the cylinders off but I haven't tried it myself.

Hmm, the US 3.2L cars were 9.5:1, I think and had 217hp, and the Euro spec cars had 10.3:1 and had 231hp, so and increase of .8 gave 14hp.

premuffler vs catalytic converter too

and different dme programming. I really don't think that compression increase was responsible even for the marjority of 14hp.

Why not just put the DME on the motor with the 20/21 cams in it instead of tearing down two motors.

Take the other motor and put in some pistons with deep valve pockets and change the cams (and rod bolts) and you'll love the motor. The 3.2 heads flow really well so you don't have to do anything there.

I know you can also use the DME for ignition only and run webers, you could get a splitter and a c2 dizzy (do they spin the same direction fellow pelicans?) and have twin plug pretty quickly if I'm not mistaken. If I am someone will correct me. ...assuming you still have the DME from engine 1.

What octane fuel can you get in your neighborhood?

I have 92-93 octane here.

My 3.0 with GE60 cams, webers port work by Walt at C.E., compression at 9.3:1, SSIs and factory pre '74 muffler etc. is a happy engine that probably pumps 245 or so at the crank. It dynoed at 212 at the wheels.

I think the cam setting was changed as well (not sure since I didnt look it up)

I have made the DC40 cams (mod-s) for 3.0 or 3.2 engines using Weber or PMO carbs. With Webers the best results are with the normal 102 lobe seperation. With the PMO's a wider angle (108) seems to work better. To be safe I would stay under 10-1 compression ratio with the Weber carbs.

These 102 and 108 lobe sep DC40s can't use CIS/DME design pistons, can they?

No these cams will not work with factory CIS/DME pistons.

Makes sense. I'm sure they make a very fun engine, especially in a lighter car!

I just built a 3.0 with 10.5:1 RSR pistons, Camgrinder's GE-60 grind, twin plug dizzy and 46 mm PMO's. It made 255 hp at the axle, runs well on 93 octane pump gas and is very steetable. When I nail the throttle, it takes off like a Rocket.

Instead of going to higher compression, which will require better gas and if it gets high enough, twin plugging, have you thought about going with 3.4 or 3.6 P/C's?

Increasing displacement is a sure fire means of more power, and you could keep the compression around 10-1, which lessens your chances of pinging if you get substandard fuel and you would as well get a nice increase in torque.

Just an idea.

JoeA

I spoke with John at Engine Builders Supply yesterday and I think I am going to go with the most bang for the buck option and not get too crazy here. He recommended going with a 9.5:1 JE piston so we don't have to modify the Mahle cylinders. Add GE60 cams and then save weight with a lightweight clutch and valve springs.

I think twin plugging is really out of the question right now. Some day I would love to go with EFI but that is not in the cards right now either.