3.2 to3.4
 

3.2 to 3.4. Mistake or not?

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

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

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

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.

Re: 3.2 to3.4
 

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

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

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

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

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

My pretty healthy single plug 3.4
http://forums.pelicanparts.com/uploa...1141874180.gif

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.

http://forums.pelicanparts.com/uploa...1148056781.jpg


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

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?:D

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)...

http://forums.pelicanparts.com/uploa...1153664429.gif

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

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

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 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.

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...

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

Steve,

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

Thanks
Scott

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

Well, I'm obviously biased and couldn't resist the urge to keep my big mouth shut, but I find the above opinion about half-true...:)

I agree that twin-ignition should be used with such a large cylinder bore, especially in an application with higher compression, CIS/Motronic and/or running pump gasolines. Twin-ignition, while not inexpensive, is certainly not a problem in my view. Far from it, not only will it increase power, provide better fuel economy and result in a crisper running engine, it provides an extra safety margin against detonation. I did some dyno testing on my motor a few months back with only the upper bank of plugs firing and the difference was over 15 horsepower! This was with Steve Wong at my side programming for both single plug as well as twin-ignition. I find twin-ignition to be a real godsend, especially with 91 octane gas and sweltering SoCal summers...:)

While the cylinder walls do indeed get thinner and the engine case spigot bores have to be enlarged from 103mm to 105mm to accept the larger cylinders, any long-term reliability problems are much more likely to crop up in a 930 or other forced induction application where higher temps and stresses come into play that may not be an issue in normally aspirated applications.

These concerns led Dieter @ Andial to design in conjunction with Mahle the 3.5L long-stroke motor used primarily for 930 applications, which is a modified 98mm bore piston/cylinder combined with the 964 3.6L stroke crankshaft. This still allowed a significant increase in displacement over the 3.3L which increased the low-end torque and reduced turbo lag prevalent in these motors, especially in the '80s when turbo technology was nowhere near what it is today (a modified K27 was the hot set-up back than).

I would offer the exact opposite opinion as Wayne. I would be much more leery of a 3.0L to 3.5L SC based motor using mechanical CIS than a 3.2L to 3.5L Carrera Motronic version where one actually CAN precisely customize the fuel & timing characteristics (see Steve Wong).;)

I would like to know how much more expensive and easier it is to program a 3.4L chip vs. a 3.5L chip. The answer, it isn't any more expensive nor is it any harder...Steve will perform his wizardry based on the engine specs you provide him and will continue to make improvements (both part & full throttle) based on your dyno plots and feedback until it is where both of you want it. Can this be done with the same precison using mechanical CIS? :)

With any motor rebuild, whether stock or race, the success or failure usually lies with the quality of the parts used and the skill and attention to detail of the engine builder...

Wayne, how about a friendly wager as to how long my personal motor lasts? Never mind that I have seen many 3.5L's over the years last well over 100,000 miles, I would assume by the recommendation you gave that you have seen many fail long before 100,000 miles. Mine is driven daily, has 15K on it at present and accrues about 8K a year. Based on those numbers, we should still be both young and sane enough for one of us to pay up when the motor reaches 100K (roughly the year 2017)...:)

Ralph

Ralph......are you seeing 246 hp at the rear wheels?

Yes, the same Dynojet chassis dyno was used for the before/after testing and for chip optimization. Don't know (or particularly care) what the actual driveline losses are (many use 15% but is probably slightly less).

A nice 50 horsepower or so gain with a nice torque curve for street use over the original, slightly modified 3.2L motor...:)

Would have liked peak power a little higher in the rpm range and without such a dramatic drop-off but limited in what I could do...You can search some of the other dyno graphs for similar type motors built without smog constraints and using higher grades of gasoline and will find that they make comparable or exceed this motor's horsepower.

A "compromise" motor intended to pass smog for sure...:(

Ralph

indeed...

as i would be very sad if i just spent all this money and had my car off the road for 4 months in order to gain less then 15wrhp...

i'm hoping to see a number north of 300. (barely)...but i will be in no way smog legal...or alibge to any noise regulations.

and i probably won't get anywhere near the fuel mileage that you do....or idle as nice.....but it'll be worth it.

would love to see some pics of your engine though

Being that I live in Florida, I don't have to worry about smog.......and if these fart exhausts that the import tuners use....or the "loud pipes save lives" Harley guys are any indication, noise isn't much of an issue in the good ole Sunshine State either. That said, i don't think my ears could handle open pipes and i would like to be able to hear my stereo a little bit, so i will probably forego the straight pipes or race mufflers. I'm currently installing the Fabspeed Euro setup with the single out muffler, but that will probably be replaced in a year or two with the SSI or B&B header setup with multiple outlets.:eek:

just so ya know the stainless steel headers probably make as much differance as the muffler does.

they are way way louder, regarless of the muffler, and to make really good use of them, you'll need a muffler which is also failry free flowing (fabspeed is probably), so the noise level will defiently go up.

If I decide to go with headers down the road, I will put the second outlet on the Fabspeed. I wanted to leave the rear valance intact for now.

I was passed by a rsr (74ish Yellow 11 rear flares whale tail) going on the 405 & Mulholland.

What exhaust does that car have guys?

It was nice and loud too.

Apologies for digging up an old thread...

As per another thread of mine, i'm weighing up 3.4 options at present - having scoured Andial's website again, i see they do a Motronic 3.5 P&C kit at 9.8:1CR.

What i'm reading above is that twin-plug is a firm requirement for a 3.5 cylinder, is this correct?

I'm UK based, so have access to decent fuel; with this in mind and running at 9.8:1, is 3.5 single plug do-able?

Cheers all

I would say that a single plug 9.5:1 is do-able with good fuel. I've even done some 102mm 3.0/3.2 at 9.5:1 just fine. The nice thing is as the bore gets larger, you need less and less dome to get the desired CR, which gives you better and better flame front propagation. Not to say that twin plugging isn't worth doing, but not a must as long as you are not overzealous with your CR demands.

Thanks Charles, thats good to know.

I'm tempted, but unsure whether trying to achieve at euro spec CR of 10.3:1 is worth attempting, or leaving at 9.8:1.

More research required!

SP

since a top end is looming with #4 exhaust leaking down 19%, its already become "while yer in thar" type of mind set. really dont know if i'll be happy just building a "bulletproof" showroom stock 3.2. its not like were chasing points or trophies and showroom stock is/ was a great guideline to follow. my wrench states i have 25000 miles left on it before power goes down or i become a mosquito fogger so i have some time to think this thru. 120 K on it now.

but while yer in thar sure opens up a can of worms to reliability and the dreaded summer heat here in the dezert.

if i just go 3.4 with some 964 cams and other assorted goodies do i start down the slope of less reliability?

if i go 3.5, am i building a grenade where temps soar and reliability go out the window?

can you still get 250K miles out of either a 3.4 or 3.5?

my track temps on the hottest days here with a setrab in front, along with fender cooler and engine cooler NEVER see above 210 pinning the hell out of it at firebird, pir or calif mtr speedway. even when going putt putt in gridlock with a/c on does it get above 210 degrees.

so really im looking for reliable bang for buck. jeremyd's seems like a good combo thats suited for track and street/highway.

open to all suggestions aside from going to 3.6. at that point i'll just buy a roached full blown sunroof delete coupe stripped down for track only and then try stuffing both into a 2 car garage thats got so much crap in it only one fits in there now!

im willing to leave no stoned unturned and money is not a question. reliability is job numero uno. its not a daily driver in the dreaded summers but i still have to traverse dezert north south east west to escape this hell hole in the summers for relief. and when its 118 degrees plus its already 105 degrees by 10am so early starts out of town are the norm.

also since its a "collectible" smog -emissions are not an issue.

open to ALL MONEY SINKING CRAZY IDEAS!

Mine works pretty well - no track oil temp issues even in hot and humid sebring.

I'd try and find some mahle 9.8 to one slip in 3.4's - talk to camgrinder on what grind he recommends -

Lots of options - start acquiring parts... :)

i've spoken to a couple of European indies, both reckon 11.1CR is safe on single plug, with 98Ron fuel and Motronic pistons

Seems high to me?

Yup, too high to me. I think part of the illusion is that the advertised compression ratios are actually quite lower than the real ones plus another consideration is that the static and dynamic compression ratio really honestly much be considered when setting fuel and ignition requirements. I've had some customers only able to run 8:1 on the four cylinder engines with one particular cam (no overlap, dynamic ~= to the static) where on another cam, 10.5:1 static or more still has less dynamic compression than the previous static 8:1 engine with the same 91 octane fuel. See my reasoning?

hmmm, kinda....but that's because i'm a dimwit...

One of the indies is a Mahle dealer in Switzerland and one builds (air and water cooled)engines for customers in various Porsche series here in the UK, so i'd trust their judgement too.