Engine Build 3.2 -> 3.4 - What do you think?
 

So as I've gone down the road on this engine build, I got a little "while I'm in there" syndrome and made a few changes. Here's how it's shaken out so far...

Pistons: 98mm Mahle 9.8 compression, Max Moritz style
Cylinders: 95mm KS, to be sent out to EBS for bore out to 98mm
Cam: Web 20/21
Rod bolts: ARP M9
Crank: 930 Std/Std (When we opened it up, that's what was in there)
Case: 930 (When we opened it up, that's what was in there - identical to Carrera case though)
Head Studs: New steel
Heat Exchangers: Stock Carrera
Muffler: Stock Carrera
Intake: Stock Carrera

Am I missing anything here? Any suggestions? The intention is to do a Steve Wong chip after the hardware is sorted out. Any guesses about how much power this setup will put out? I'd like to do a less restrictive muffler setup, but I haven't been around other folks cars enough to know what I like and what I want. Motor is intended as a fun street setup, maybe some DEs.

The new (used) Mahle pistons:
http://forums.pelicanparts.com/uploa...1442433427.jpg

Hmmm... With a sport muffler, you could be in the 260-270 range. SW once suggested that even the most vanilla 3.4 setup can get there. It is debated, but an open cup style sirbox and fresh air filter may add a few hp post tuning. I enlarged my throttle body to 66mm also. Prob overkill, but while you are in there...

I agree with snake dude with that kinda work , if you let it breath a bit more even headers with sport muffler and a properly tuned sw chip.. You are talking maybe 20 more low end seat of pants hp/torque woohoo would be a shame to leave that on the table. Can be done with little added noise also just my 2 cents

Do you have an original 3.0 engine in there or is a a 3.2 retrofit?

Stock Carrera should mean Motronic.

Probably too late now, but have you looked at the rothsport 9.8 compression 95mm pistons built for stock Mahle nikasil cylinders? That's the super hot 3.2 set up now and will save you some serious $$$.....more than enough to get a GT3 oil pump in there which is a must for sharp end track use

Won't get you 270bhp, but you'll have that at the crank using 91 octane.

Yeah, a low restriction exhaust is the plan. I just need to listen to more cars in person to figure out what I like. I'd prefer a system on the quieter side. Any suggestions?

Yes, the engine is a 3.2 retrofit with Motronic.

I like it.

I'm building essentially the same but a 3.2 from a 3.0 CIS with the MM 98mm wedge Mahle pistons.

If you haven't yet purchased your Webcams, consider Dougherty cams DC19 profile. It's the same profile as the WC 20/21, but he'll grind them on your stock cams. This will save you some dough.

Also, due the aggressive ramp of these cams (DC19 or 20/21), aftermarket springs are recommended. I'll be using the Eibach 20444.212 http://www.summitracing.com/parts/eib-20444-212/overview/

Thanks Josh. Already have the cams, got them for a pretty good price. Do not have springs... did not know they were required/recommended.

So I did some quick googling, not coming up with any info on this. Can you point me in the right direction?

Josh, if you did not bought your springs yet, or tmaull, if you are planing on buying these springs. I have a brand new, in box Eibach 20444.212 set, that I purchase from Summit when they were cheaper and did not installed them.

I can sell them for $100. Just trying to get back what I paid for plus freight cost.

(Sorry if this goes against the forum rules, and I'm not using the classified section. I did not intend to sell these springs, and to keep them for a future project... but if it could help some fellow Pelicaners...)

The Rothsport site says they're NLA?

Buy Hugo's Eibach springs and pick up some Aasco Ti retainers from EBS. That's probabyly the best deal out there.
I'd go bigger with the cam, since you should have plenty of clearance with those pistons.
Supertec has some oil pump mod for the 3.2 pump that sounds like a good idea, if you're not going wild with the revs and don't want to go all out with a GT3 pump.

So I already have a the cam, and I think it's a good solution for me. After all, this is a street car. Hugo, sent you a PM.

As an example, AASE Motors built a similar motor last year, Mahle 98s, single plug, 964 cams, modified cone filter setup, and the full stock exhaust and muffler, nothing else. If the motor is built right, it should dyno at least 230 rear wheel hp SAE on a Dynojet. This motor dyno'd 236 at the rear wheels after a remap, or about 270-275 at the flywheel (blue curves below). Red curves were with the stock chip.

http://forums.pelicanparts.com/uploa...1442515291.jpg

AASE has just finished a revision of the motor in a slightly different configuration with 10.5:1 custom pistons, twin plug, DC 993SS cams, and will be retuned again shortly.

I helped on a motor very much like what you are doing with great results:
http://forums.pelicanparts.com/porsche-911-technical-forum/851912-my-87-3-4-maf-project.html
see post 63 for final dyno numbers.

I agree with SW that hitting better than 230 WHP should be no issue if done correctly.

Here's my thoughts based on few builds I helped on that had excellent results and perfect street driveability.

Consider 964 cams or DC 21 Cams also.

SSIs work very well on this setup, I know some will disagree but a 3.4 motor I did early this year showed otherwise. Or use B & B Headers and dual out mufflers 1.75 inch primaries. My personal engine is a 3.2L Euro and dynos in the 228-232 WHP depending on season and temps I also have SSIs with no issues at this power level my engine also has those Web 20/21 cams.

Bore the Throttle Body and possibly consider MAF.

I believe they are controlling distribution. I think they want the customer to send them their cylinders so the pistons can be properly fit. Rothsport markets it as a package deal and is surprisingly (comparably) inexpensive.

This is the 3.2 spec for the PRC Spec 911 class. About the same output as the POC Spec Carrera class motors (235bhp/205tq), but they get it running pump gas.

SSIs are too restrictive on a 3.4. I have dyno'd tuned many 3.4 and 3.5 motors over the years that had them, even engines built with every trick in the book by the best of air cooled engine builders, and the motor struggles and chokes off by at least 10 hp over the factory stock exhaust and muffler. Same motor going back to the stock heat exchangers and muffler, and either a premuffler or sport cat, and an instant 10+ hp and a broadband increase in torque.

Also, extensive tests I have done, along by others have shown no HP increase with a MAF on the 3.2s and 964s, which have the same air flow sensor. None, not even one hp at 7000 rpm at full throttle. Tests I've done were in the scientific method going back and forth within minutes on the dyno, equalizing air fuel ratios and ignition timing to identical values, using the trickest MAF setups one can imagine. The restriction of the intake is not the air flow meter, but the airbox and snorkel attached right before it. We have also done extensive tests on air filter setups, and we use a modified and ported version of the cone air filter setup from MSDS which eliminates this problem creating a large bell mouth velocity stack into the air flow meter, which is superior to standard standard straight tube MAF sensor setups with a standard cone filter on the end. Anyone that dyno's a difference between an aftermarket MAF vs the stock AFM setup is really just comparing the difference with and without the stock airbox setup.

Thanks Steve. 230rwhp sounds great to me - about what my STi did. So I'm trying to make a decision on springs/retainers. My springs meet spec and my engine builder thinks I should stick with what I have. Higher compression springs means greater cam wear, etc. How much of a difference is it? What will be the difference in performance/reliability if I stick with what I have?

Did I miss where you mentioned twin plug? It's a benefit at 3.4. This is nearly the exact motor my daughter is building. Same cams, pistons, etc. we have 1-3/4" headers into a sporty muffler that she is making into a GT3 like outlet. She's running twin plug with the Andial splitter.

From what little I know, I think cam finish and accuracy is more important with regards to wear than anything else. Not naming any names, but some cams have too rough of a finish, aren't ground level so they may only make contact on half of the cam lobe, and/or are hardened too hard, causing all kinds of strange wear within 200 miles of installation. Oil with a good amount of zddp is important, and you should have the rockers refurbished and drcamshafts should be able to do that for you reasonably.

No twin plug on this motor... running the Max Moritz pistons. Jon, what are you doing for valve springs? This is where I'm hung up right now.

I've had a stock AFM flow benched and after about 13,000 g/min of flow we have a 10 inches of water column pressure difference and if you flow any more than this 13,000 g/min start to produce intake vacuum at WOT. A 3.4L ingests about that flow rate at sea level at 20C ambient. I have the actual flow data showing this. I think that a real hot 3.5L at 7200 RPMs could easily be at 15,000 g/min and at that level of flow the pressure drop becomes far more significant around 15 inches of water. 1 inch of water is about 0.032 psi so at 15" we have 0.5 PSI of vacuum. Doesn't sound like much but add a few more PSI for the Throttle body and the intake box and it starts to add up.

I agree that the AFM alone is not the source of a big restriction until you start approaching 15,000g/min. But you need to consider all the components and the biggest restriction in the 3.2L intake is the Throttle Body, spend some money opening it up as much as possible.

But don't disregard the other advantages of MAF, totally correct fueling across extreme altitude changes like sea level to 10,000' and throttle response but the system MUST process the MAF signal correctly. You can NOT make a MAF pretend to be a AFM that's a compromise. You need to re-write the code to process a MAF signal natively.

The reason I decided to do MAF is that many AFMs are 30 years old and out of spec or they have been messed with so they no longer accurately measure air flow. The MAFs I use are all calibrated to NIST standards and registered with NIST. They don't vary by more than 1% between MAFs. So I have a 99% correct air model, then I decided to do the same for the fuel model by going with brand new fuel injectors. If you just spent $20-30K on a engine build why would you not want to have a 99% accurate Air/Fuel model? Considering the costs of these motors why not take the time to properly address the fuel/air model?

I'm not saying you can't tune AFM, you certainly can and we have good resources for doing so on this board but it's hard to tune a AFM car across the entire operating conditions, not just WOT. But if you have the Air and Fuel properly measured and metered then the math simply works like magic. In my MAF I command a Lambda (AFR) value and that's what I see at the exhaust it's very easy to work in this mode quickly.

If you want to really understand this fascinating area I suggest you purchase both books written by Greg Banish they are a wealth of information into properly tuning engines. I'm not sure why so many tuners are so secretive? Once you learn how it's done and why you quickly realize that a lot of work goes into tuning and it's not really for the DYIer. How many megasquirt installs have you seen that actually work correctly? Just go to the track and watch folks tinkering with after market EFI because it's not working correctly.

The motor above has just finished being reconfigured with a bit higher compression, and going twin plug. The pistons are also changed, as you need a different dome profile for a twin plug head, wedge dome is for single plug. You get a slight efficiency increase when increasing compression ratio (search otto cycle and analysis), and twin plugging allows you to run the reduced ignition timing necessary for the higher compression ratio when running 91 octane pump gas. The reduced ignition provides also a slight engine efficiency increase due to reduced work the engine needs to perform when pumping the piston up during the the onset of combustion after the initial spark. I don't expect much but every little adds up.

Been there, done that. Just providing the final results vs theories.

Think about what Porsche did with the GT3 RSR when given an FIA restriction of two 28.6mm restictors to their intake. The engines still produce 500 hp because of the large long bell mouth velocity stacks leading to the restrictors.

His pistons are for single plug only.

Yes, pistons are single plug only. I may go back and do the throttle body at some point, but not now. Also planning staying AFM. This is not a cost no object race motor, it's just a rebuild because I popped a head stud, and got a bit of "while I'm in there syndrome." But what I'm really trying to decide is whether I need to upgrade my valve springs. It is starting to seem like a bit overkill for a street motor. Thoughts? I've tried searching this topic, but not able to come up with much.

You zing that motor once you'll have wished you'd spent the extra $800 on ti valve springs and retainers. It's really, really, really cheap insurance.

Sorry for making an error in my earlier post, She's using JE pistons for twin plugging, not the wedge design. The heads were done right for the cams, but I do not know what the springs are, Sorry for that. I "think" EBS did the heads, I know they did the cylinders and pistons. I can dig into the paperwork and see what she has.

Additional Info on Heads:

Carrera TWIN PLUG heads - heads done by Ollies, intake ports blended, exhausts polished.

No info on the springs.

John Dougherty recommends a valve spring upgrade with profiles that have higher valve lift than the 964 cam. His DC19 cam is the same profile as the Web 20/21 and he recommends "street performance valve springs" in the notes guide. I've read some of his posts on Pelican (he goes by camgrinder) and I recall he's reasoning as valvetrain stability. Sorry, but it's the only data point I have.

Dougherty Racing Cams

I helped on the tune of this motor with DC 21 cams and twin plugs very snappy engine with tons of low end torque.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/871561-1985-3-4-build-using-maf-279-56-hp-237-63-rwhp.html
The overall torque in this twin plug was real strong. This motor will likely go to more aggressive DC cams this Winter. We are surprised how well the EFI system I did for this car can tolerate aggressive cams. Idles perfectly at 920RPMs.

And if he buys the $100 eibach springs posted earlier, and some Aasco retainers for $225, it's REALLY cheap insurance.

OK, so I went with the Supertec springs and retainers from Henry.

That leaves me with:
Pistons: 98mm Mahle 9.8 compression, Max Moritz style
Cylinders: 95mm KS, to be sent out to EBS for bore out to 98mm
Cam: Web 20/21
Rod bolts: ARP M9
Crank: 930 Std/Std (When we opened it up, that's what was in there)
Case: 930 (When we opened it up, that's what was in there - identical to Carrera case though)
Head Studs: New steel
Heat Exchangers: Stock Carrera
Muffler: Stock Carrera
Intake: Stock Carrera
Valve springs and retainers: Supertec

Anything else I've missed that I should do while it's out and in pieces? I think I've got most of the low hanging fruit covered now.
-Tom

If you can fit it in the budget, port and flow the heads. Not cheap but if done properly can have dramatic effects.

im looking into re-boring my cylinders to accept 98mm pistons for a twin plug 3.2 "while you are in there". i thought about MM or JE (not capable expansion rate?)but what type of flat top pistons are available with street CR?

regards
pf

I was just visiting with some PCA folks this past Saturday. They are building a 3.4 as well, and believe it or not, they are using Chevrolet pistons! How odd is that?

Engine rebuild
 

About 2-3 years ago, I built a 3.3SS from a 3.0 SC engine for my 1980 SC coupe. The only thing that I did different (basically) is that I used 10.5:1 Mahle pistons and Electromotive XDi twin plug ignition. I kept the CIS intake but changed it to the early box with the large bore runners and used Carrera heads. I think that you will be pleased with the way your engine runs and pulls up to redline. You probably should have the Carrera rods rebuilt, balanced and shot peened to help minimize any stress riser points.

Well I'm picking it up from Bruce on Thursday. Got a chance to drive it last week and I love it. Can't wait to put Sal's MAF system in it, and tune it.