speed rII

Thank you, logray. I somehow missed the links from you previous post. 3,7l tempting...

logray

I'm dying to come up for a reason to do it on my car...

gieseja

That is stage 7 for my car. My mechanic quoted it as: Full Motor build 3.4L to 3.6L, JE pistons, R/R connecting rods, Crankshaft, Ported/Polished Heads, balanced rotating assembly, custom tuning for dme. I believe rwhp was 316 or 330.

speed rII

Ok, that would take the hp level right were I would like it to be.

So, now that the solution is found, I have to make the funds for it
I think that I will contact the autofarm and ask for the sleeves and pistons only.
I have couple of places that let me use their milling machines...

Thank you everyone

Apex996

I'm resurrecting this old thread in hopes that I can find some more info on putting 3.4 heads on a 3.6 block. Does anyone know what needs to be changed (specifically) to do this? I am not interested in other engine configurations. I am specifically interested in the changes required to put a 3.4 VC1 head on a 3.6 block. I will be retaining my wiring harness and cable throttle.

speed rII

I never went thru this, and still running with 3,4l.

If my memory serves me right, you can get the 3,6 from 3,4 just by changing the crank and rods from 3,6l to 3,4 block. Allso your IMS tube must be the one with newer chain from crank to ims.

I believe that JrGordonsenior has this setup in his racecar??

Apex996

Anyone know if the guide pin locations for the chain rails in the head are the same ? Combustion chambers of the 3.4 and 3.6 heads are different. So I wonder if the over bore vendors (LNE etc) have different piston designs to compensate.

Amille28

Here is what I think. The boxter S 3.2, 911 3.4 and 911 3.6 engine case halves are pretty much all the same. The 3.2 engine has a smaller bore than the 3.4 and 3.6.

Heads on the 3.2 and 3.4 appear to be identical. 3.6 heads are VarioCam+ yes Porsche could have varied the chamber size over a few years to mess with the compression ratio. You could look at the specs for the different engines to get the compression ratios for each MY. I think you could deck a pair of 3.4 heads to increase compression ratio but may run into problems with the limits of the camshaft chain tensioners.

There is also a stroke difference between 3.4 and 3.6. The bearing cradle, IMS shaft, crank, and rods could conceviably be transplanted into a 3.2, 3.4 or 3.6 case to increase stroke.
of course if you sent your stuff to LN engineering and got the 99mm bore increase with a 3.6 cradle/crank/rods in a 3.4 case with 3.4 heads you would have a 3.8 engine.
I do know that from researching this that some of the oil passages on the bearing carrier assembly are different on the 3.6 than the 3.4. I am not sure if this was just a upgraded design change to account for better flow within the bearing cradle or if it would have some adverse effect. I plan on contacting Porsche to ask.

I think that VC+ is a cool concept but it is way too much trouble to change the computer system to get it all to work ....key word.. correctly. Just give me more displacement and I will be happy.

I know there is someone on here who went with the thicker walled 3.2 boxter case and 3.6 bearing carrier to net 3.4 (bulletproof). I wonder if they could chime in here.

research the Porsche parts catalog and look at what parts are used on what years... its not always all inclusive and i think some modding might have to be done to get this to work with that... but all seems to be doable.

Apex996

Thanks Amille28,
I've heard a few have done exactly that. Drop the large stroke carrier into an earlier case. I'm curious about the details surrounding the pistons & combustion chambers. Sure it may work just bolting those parts together, but I'm looking for maximum power so valve clearance (high lift cams) and piston crown to combustion chamber shape matching are of concern.

I have yet to find real details on what guys have done with the pistons in a 3.6 case with 3.4 heads or in an LNE type of 99mm bore (JE) 3.4 to 3.6L configuration. Do guys buy the JEs for 3.6L to get the correct pin height and then compromise on the chamber shape? or ...

I've tossed a few pics in here to show those who may not be familiar with the differences between the 3.4L and 3.6L cylinder head combustion chambers.

The first (left) shows a dirty 3.4L type chamber.
The second a side by side of the 3.4L and 3.6L. The 3.4L has obviously had a skim cut to clean things up and custom stainless valves.

I'm going through the analysis phase of a project, comparing 3.4L, 3.6L and GT3 parts. Interesting to see what the similarities are.

I agree with you that the VarioCam+ isn't worth the trouble. I'll take the '99 electronics with actual cable throttle and easier to tune DME. The 3.6L valves look badly shrouded in the head. Plus the more "normal" 3.4L cams are cheaper to have ground. I also agree that displacement is the way to go. I originally wanted to keep the short stroke (78mm) of the 3.4L to get something that revs more like a GT3 (76.4mm). However after thinking about it I don't think the other engine parameters are suited to make more power up high.

Flat6 Innovations

We create these types of "mutants" frequently. It can be done and can have benefits, but there are things to overcome that are quite challenging.
The biggest difference is the timing chains, which require case splitting to swap out.

A big consideration are the valve reliefs in the pistons. You won't really know what you have to overcome until it runs for the first time. I worked through this years ago with zero assistance and it wasn't fun.

Amille28

Jake is right and is the specialist on the topic. It looks like the chamber (quench) area of the 3.4 head is smaller than the 3.6. That combined with the increased stroke of the 3.6 bearing carrier assembly could and probably does lead to valve/piston clearance issues. It could be done but you would have to really research the clearances.
Additionally the x51 package from porsche changes the duration and lift of the camshaft. This was a package with aluminum intakes, heads, upgraded ims. Do a search as someone posted dyno sheets with stock then stock X51. I think this franken-engine combined with a cam regrind closely watching valve lift could get you to the 360hp goal. How cool would it be to turn your 3.4 into a poor man's cup car. Downside is that the X51 was a really expensive mod and not even sold in the 3.4 version in the US. You might even be able to get a lopey cam duration that would have made Dr. Porsche throw up in his mouth a little hearing it.

Apex996

Agree on the quench area comment. That's why I was asking what people have done with the piston top design. Anyone know the pin heights on the 3.4L vs 3.6L pistons? If I recall the 3.6L rods are ~3mm shorter.

>> You won't really know what you have to overcome until it runs for the first time.

If one were just throwing parts together I'd agree.

I'm familiar with the X-51 and will not be using those components except for maybe the int & exh manifolds. There are no X-51 cams for the 3.4L US spec heads. I need to get the heads cleaned up and cc the chambers. I'll post the #s when I get to that stage.

Measured the included valve angle last night. 28° just like the GT3. Bodes well for using GT3 porting data as a guide. But we'll cross that bridge when we come to it.

Amille28

Check this out, good thing im kinda fluent in German. I found the OEM company that makes the camshafts and found the pdf link to their catalog. Here is all of the different durations, lifts, and even prices of the cams.... Anyways Ventilhub is the German word for lift.. you can see that there are several different cam profiles for the 3.4 engine. Looks like stock lift was 10.7mm. The words "verstellbarem Kettenrad" mean adjustible chain wheel and so it has a range on the duration. I am thinking this means the range at which the chain tensioner can vary duration. Stock 3.6 lift looks like either 11.5mm or 12.0mm

the link
http://www.avl-schrick.com/dat/MK/Sc...202009%20D.pdf
best translator english-german
dict.leo.org

I'm still looking for the piston info.. seems they are made by Mahle OEM but they arent listed on their website.

Apex996

What you're looking at is their motorsport catalog. And while it's fun to read it in the mother tongue (ein bisschen) you can also get a copy of the English version:
http://www.avl-schrick.com/dat/MK/Sc...202011%20E.pdf

Yes the pistons are Mahle.
And yes the cam specs are given for "large stroke" and "small stroke" or the delta between full advance and initial timing advance.

Stock lift on the 3.6L is not 12mm as that's a high lift race cam. 3.6L is either 10.7 or 11 at most. I dont have that spec with me atm.

For kicks, here are the X-51 cam specs for the 3.6L

X51 Cam Specs
ATDC/ABDC/BBDC/BTDC
Large Stroke IO, IC, EO, EC
9°/61°/50°/4°
Small Stroke IO, IC, EO, EC
39°/19°/50°/4°
Or
9°-39°/61°-19°/50°/4°

I have been looking at Schrick, DeBilas, and FVD cam specs.

Apex996

Can anyone point me to a part# of the Harmonic Dampener Porsche uses on the 997s ?
Anyone making a smaller dia. or lighter harmonic dampener?

I see RSS makes one but it says: Fits 997 mk1 3.8L Models Only. Need to inquire about that.