3.2 to3.4

[nate3.4]

3.2 to 3.4. Mistake or not?

[Steve@Rennsport]

Good idea if you do it right (Mahles),....

You might need twin-ignition, depending on what your local octanes are.

[Shuie]

talk to rdane. If its still for sale, buy his 3.4 and save yourself a lot of research, time, and money.

[rdane]

A 3.2 Motronic as a 3.4, as Steve mentioned, can be a great engine.

Mine is a 3.4 CIS. BTW they are 3.364 IIRC and a nice engines as either Motronic or CIS.

[Carrera3.5L]

Originally posted by nate3.4
3.2 to 3.4. Mistake or not?

Buy 100mm Mahle's instead of 98's and maximize your displacement without changing the crank or rods. Makes a "true" 3.5L (3506 cc) that is 10.8% larger than your current 3.2L.

Mahle 100's are cheaper right now than 98's, use the extra money for the case machining (approx. $200) and a good 40%-50% down payment on the twin-ignition components/machine work you will need.

Will definitely make more power than a 3.4L all else being equal for probably the same cost or close to it.

Or simply sell your 3.2L if in good shape and do the 3.6L transplant like most people and make even more power.

Ralph

[ChrisBennet]

BTDT. A 3.6 conversion is a much better value IMO.
-Chris

[cnavarro]

I'm with Ralph, a 3.5 conversion is a great engine. I've had customers get away with keeping a single plug though, and running a lower compression 9.3-9.5:1, to keep the cost of the conversion down, even on bore sizes up to the 102mm (3.7 conversion).

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

[Dadofour]

What kind of hp does a 3.5 deliver? Is it dependent on whether you use the motronic or go with Carburetors?

Thanks. I just finished a stock 3.2 rebuild and I will be starting a project on the stock 3.2 I took out of my car. I am in no rush and would like to put together a nice engine using the 3.2 as a starting point.

Thanks

[Facey]

on bruce anderson's how to build a porsche 911 engine, in his favorite engine sections he speaks of a sc (3L, alum) block, with 100mm mahles P&C's, with a 3.2L crank to make a short stroke 3.5L monster wtih 46mm webers and stuff like that....it includes twin plugs, hi comp.... i don't remember what he says the output is, i recal something near 350...actually he might say over 350....

anyways chris streit of moto delta (i think he runs in like GT2 or 3 NASA class, and crushes it).... he is running a 3.3L whihc dynoed ~270 rwhp.....and this was still during its intial setup.....and he might onyl be running 10.5:1 comp....not the 12.x:1 bruce mentions..

i just thought i should also add, that i ahve owned a high output 3L, and it was a nice engine, lots of bite to go with its insane bark.magnesium case with JE P&C's, flowed CIS head, SSI's, MSD isgnition, machined head work, early S cam, new valve springs free flowing muffler. great engine.

edit: didn't realise chris was running the stock 3L crank

[JeremyD]

My pretty healthy single plug 3.4

[cstreit]

I'm using lnengineering 100mm cylinders with J&E pistons on a 3.0L case and a std 3.0L crank. The case was bored out slighty to accomodate. 46mm webers and early SC port heads. Results in 3.317L motor.

I've twin plugged for safety, running 10.5:1 and 93 octane fuel except on the hottest of days where I mix 50/50 with 100 octane. Car is making 312HP at the crank at 6500RPM (motor is built to withstand 8500).

Mind you a 3.2 wouldn't handle this cam so the pistons ,induction, and cam are your ultimate limiting factor. If you're going to build up, you'll need some induction work and pistons to accomodate a more aggressive cam and use the potential of your motor.

Here's the dyno. I expect a bit more this time around fixing the high-end lean issue.




BOTTOM LINE... I'd max out your displacement (short of having to mill the case) to make wise investment.

[jdm61]

Originally posted by JeremyD
My pretty healthy single plug 3.4

Ain't 93 octane florida gas great? lol. You kinda got me hooked on this idea, Jeremy. I had an evil thought. i can get the blue 100LL avgas pretty easily. wonder what that would do?

[Carrera3.5L]

Originally posted by Dadofour
What kind of hp does a 3.5 deliver? Is it dependent on whether you use the motronic or go with Carburetors?

Thanks. I just finished a stock 3.2 rebuild and I will be starting a project on the stock 3.2 I took out of my car. I am in no rush and would like to put together a nice engine using the 3.2 as a starting point.

Thanks

Yes, the horsepower is dependant on whether you retain Motronic or change to carbs or itb/engine management. Your cam choice will also determine the engine's characteristics.

Here is a dyno chart for a basic 3.2L to 3.5L twin-plug conversion with Motronic using mild cams running on 91 octane. This motor passes CA smog no problem but in doing so leaves alot of power on the table. Different induction and cam profile if smog requirements were not part of the equation as well as better than 91 pump gas would increase these numbers significantly...the torque increase is appreciated as the motor begins to pull from as little as 2,500 rpm now. A VERY nice motor for daily street use (especially in a relatively heavey 2,600 lb G50 Carrera)...



This is the before/after on the same dyno 3 months apart (the length of time for me to build the motor and do a 1,000 mile break-in). The initial set of runs is the 3.2L with SW chip, Dansk pre-muffler and Dansk final muffler.

3.5L with carbs or itb/engine management and a complement cam profile with better gas will make 100 hp/liter. It's not wading into uncharted waters either...these types of motors have been built for over 20 years. We did a 3.5L slide-valve motor at Andial many years ago that made 375 on the engine dyno for a customer in Mexico City...

Ralph

[Facey]

howdy.... thats what i'm shooting for...100hp/L

i can get gas up to 97oct at the street pumps.

i have no smog or noise requirements. 12+:1compression
using a high lift cam with a ported engine, big webbers, B&B headers witha free flowing M&K muffler...should be sweet.

it'll be on the road before middle of august... hopefully on the dnyo not long after break in.

cheers
Nick

[Jeff Alton]

Where are you getting 97 octane at the pump?

Have you measured the CR at 12:1? Still seems a little high for 97 octane. Love to see the dyno chart when you get it broken in.

Cheers

[s5uewf]

I increased my 3.2 to 3.4 this past winter with Supertec's expertise and services. I am slated for dyno runs tomorrow to give me A/F so SW can further refine my chip.

I'll be able to give you some more basic 3.4 HP/torque data maybe tomorrow night.

Basic spec's: 3.4 Liter, Webcam 20/21 cam, Motronics, 9.5:1 CR.

[Facey]

Originally posted by catca
Where are you getting 97 octane at the pump?

Have you measured the CR at 12:1? Still seems a little high for 97 octane. Love to see the dyno chart when you get it broken in.

Cheers

I'm located in the middle of Vancouver Island, B.C.
The local chevron has a 95~96, and there is a gas station near my hosue owned by the local track guy (saratoga speedway), and he sells a 97, as do the 2 mohawk's in town..... it's an ethanol addactive, but its rating is 97oct -0.5, +1.... thats pretty good.... good enough for 12.something to 1....

ya a dyno garage just opened up in the riv.... havb;t been there yet, but i got a buddy witha TT rx-7 thats got the high hp on the stand so far (542 to the rear wheels, he's running 1.6bar (t78) with peak power at like 8500rpm.

anyways, i plan on taking my truck and the porsche there when ready....seeing how the 3.5L compares with a cammed up 327...

[Jeff Alton]

Cool! The guys with the dyno I will be using are RX7 TT guru's as well! I hope to make a little over 300 at the flywheel....

Cheers

[Scott Wolthuis]

Good idea if you do it right (Mahles),....

Steve,

Are there known problems with good used 98mm Nikisul using J&E pistons @10.5-1?

Thanks
Scott

[Wayne 962]

100mm cylinders expose other problems, mainly the need for twin ignition to achieve good performance across such a large cylinder. Also, at 100mm, the cylinder walls are getting very thin, leading to reliability problems.

I would recommend 100mm for a street motor not running Motronic, as you can't easily customize the timing or fuel characteristics of this system without an expensive and difficult to program chip. The 98mm pistons and cylinders can be made to work with the existing 3.2 system quite well...

-Wayne