Hey safe,

Shimming is done at the cylinder base and yes it does marginally increase the total combustion area to decrease the compression ratio. To my knowledge the Motronic piston hump was designed to improve combustion efficiency thereby reducing emissions. Unlike other higher compression domed pistons it does not tend to divide the combustion area in two, but rather compensates for the plug location. That said I can see advantages running with the Motronic piston with a one plug set up, over other piston designs when running a low boost set up. Personally I don't see any pre-ignition issues.

Similar
 

I did something similar:

Valve guides - what started it all :)
3.4 mahle 9.8
Ported the cylinder heads
Extrude hone intake
Boat-tailed the case
Performance cams
ARP rod bolts
Enlarged throttle body
Mass airflow sensor & custom chip
Jerry Woods valve springs and retainers
Bursch muffler

It pulls really hard now (harder then the 87 turbo)

Ditto, same here it all started with doing the valve guides!
At first it was just going to be a stock build, but then you get in there and think well I might as well do a bit more to it while were in here. Next thing you know your hooked! :)

Today I ordered Thermal Barrier Coatings and Dry Film Lubricants!
Man this is a lot of fun but so addicting once you get started.

I like your build, what chip are you using?

Ditto, Ditto, same here it all started with doing the valve guides!

Then I really got carried away :eek:

Spec:-

3.5L Nickies
10.5:1 ceramic coated JE pistons
Twin plugged (did my own machining)
DC20 cams
Large throttle body
32lb injectors
Dumped "barn door" air mass meter
Fitted SDS engine management system
Six coil direct fire ignition with Magnacor leads
SSI headers
Dansk 2 in 2 out SS exhaust (loud)

265 - 277 flywheel BHP:)


Why the variation in BHP? It depends which dyno shop you go to.

It pulls like a train and has good throttle response, but I am still uncertain about those injectors, I feel that they don't atomize properly and I could get more out of this set up.

Paul, if you can stretch to it you should go twin plug it seems to make a considerable difference to my motor. The ignition advance on my motor has come down to 24deg BTDC and if I pull the coils for the second set of plugs it won't tick over so it clearly has an effect on combustion efficiency.

good luck with your rebuild, Pete

To be honest, the best bang for the buck is to just loose weight, that helps everywhere.

For sure Weight to HP is everything.

I'm putting her on a diet!!!! The following is coming out
A/C, compressor, mounting, etc, no use for it, power robbing dead weight.
Cat, heat exchangers, engine mounted blower motor for heating system,
heavy muffler, Its my summer toy who needs heat anyway.
Cruise control, never use it,

I'm sure this list will grow! :)

Thanks for you input Pete, Excellent build! Very nice, love what you have done!!
I'm interested in learning more about your ignition set up.

Re: your fueling needs. What is your injector rail fuel pressure at? Lots of guys doing 3.2 turbo conversions are running a variable rate pressure reg with the stock injectors into the 400 HP range, or with your set up probably a 3bar reg would do the trick if your injectors are still spraying a good pattern.
What are you’re A/F at now, do you have a wide band O2 and a data log?
I see your running with Ceramic pistons, from what I’m reading this means you’re A/F ratios can run leaner and near the optimum range for max HP.
I’m also concerned about running the injectors beyond there capacity and looking into Water alcohol injection for charge cooling, eliminating pre-ignition ,lowering detonation threshold and providing supplementary fueling.

Check these guys out http://www.rbracing-rsr.com/waterinjection.html

I see you machined in your 2nd plugs, What were the angels used? I'm considering doing my own also, for future use.
This time around I sticking with the motronic dome piston and it will not work with the 2nd plug, the hump is right where the 2nd plug goes. I'm ceramic coating the pistons and combustion chambers myself with CBC2 Powerkote, according to them you can run up to 13.5/1 CP with up 1bar boost with this product. The advantage of CBC2 over CBX is that you can polish it, to further improve flow and reduce detonation threshold. So for my high CP low boost application it was the better choice

Here is a link to the coating mfg http://www.techlinecoatings.com/BulkEngine.htm

Hope to learn more about your step up, thanks again Paul

Pete try searching on the turbo forums for injector info. This is some of whats over there, hope it helps Paul

Posted by mlhm5
*500cc per minute is approximately equal to 49lbs per hour which is equal to approximately 100hp.
* lbs/hour = cc per minute / 10.5
* lbs per hour = HP / 2.04
* cc per minute = lbs per hour x 10.5
* cc per minute = HP x 5
* HP = cc per minute / 5
* HP = lbs per hour x 2.04



Injectors Speedy Squirrel
Type: Siemans DEKA VI
Flow: 4.8 to 5.0 gm/s static flow at 300 kPa
Tip: Extra Extended Tip (17.5mm)
Spray: Pencil type, no bend

For a comparison, the stock k-jectronic injectors are flowing around 3.9 gm/s at 300hp(flywheel)@5500 RPM.

The formula I use for sizing injectors is:

Flow (gm/s) = (target flywheel HP)*0.0790/(number of cylinders)

I was shooting for around 400HP at the flywheel, so that comes out to 5.2 gm/s, which is how I arrived at my injector size.

For 650HP at the flywheel, you get 8.55 gm/s (67.7 lb/hr), so the injector size depends on how much power you want.

Be realistic! Bigger is not better. The reason is that a large flowing injector performs very poorly at idle. The pulsewidth becomes so small that the injector can't handle it. Rather than spraying in a small amount of fuel, it just shuts off.

65 lb/hr is probably the biggest that most people on this board will need. 85 is ay too big, unless you're making over 800HP at the flywheel.

Nothing wrong with designing to run at 100% duty cycle at max power. That's when the injector is running the best! Flow is not interrupted, just one big garden hose of fuel spraying in.

Pay attention to the spray pattern. All injectors are NOT the same. Most multi-intake valve engines actually have two narrow sprays coming out of one injector. Put those in our motor and you have two narrow sprays onto the port walls. Not Good!

Hi Paul,

Firstly the ignition set up is two banks of 3 coils. These are the double ended type that fire two plugs at the same time, (one is a wasted spark). I connected one bank to all the original plugs (top plugs) and the other bank to all the bottom plugs. Doing it this way I can turn off the top or bottom plugs by pulling a fuse to test that the plugs are firing. After my rebuild I was still running the original Motronic OEM engine management system and then I introduced the SDS engine management a stage at a time to check all was working as it should be. ( I can expand on this if anyone is going the same route). If you want a look at this coil set up there are details in the tech' manuals on the SDS site (www.sdsefi.com)

I did all the machining for the second plug myself, all the details are on these pelican forums this is where I got my angles from. I will have a dig around all my old links and post it.

I'm using the stock fuel pump and regulator and therefore stock fuel pressure. My tick over is just fine with the injectors I'm using http://www.racetronix.com/621020.html it's just that before I installed them I did a spray pattern test of the Porsche stock injector against the new one and the original seem to have a better pattern, less of a pencil flow. Not sure what if any effect this has. I have asked this question on here but had no good feedback yet.

Yes I do have a AF ratio meter, it is a WMS one and I think it's a pile of junk. It seems to be displaying the right ratios, if it can be believed, but it leaps around all over the place. Just purchased a new Innovate one with an analogue dial I hope this one is better.

Good luck with the rebuild Paul.

Pete

Chip
 

I have an Autothority MAF and the chip came with it customized for my build. Eventually I need to get together with Steve Wong and see what can be improved.

Bang for the Buck
http://forums.pelicanparts.com/uploa...1233603508.jpg

looks like hot and cold something goin' into that intake... maybe nos or a liquid ??

We need more info on this set up please... also maybe a utube sound clip of that motor in action??
Bob

Very nice Nitrous set up, very clean installation and yes your right great bang for the buck.
Where I live Nitrous systems have been outlawed to combat Street Racing :(
They are nasty here, heavy fines, impounding your car plus towing and storage etc.

So its not an option I would want to go with, besides I'm hooked on the turbo bug now.

Turbo Header arrived by Mail the other day, so no turning back now

Bob - I will make a Utube Video with the simple setup and sound clip for the curious minded.

Paul - I don't know if Oklahoma has a law on Nitrous. I have run Nitrous on this car for 10 years now. I will take the 5th if I get pulled over lol… The Turbo set up you are going with will come with a kewl Turbo whirling sound too! I hope to see some pictures of the build.
:cool:

I Bet she dances when you giver a good shot! Instant Boost & "0" lag!!!

Looking forward to seeing your Video. and hopefully without you taking the 5th.


I don't have much yet but will try to get some photos up as the build progresses.

A few Photos to share the Love

Sexy shot of OBX Header
http://forums.pelicanparts.com/uploa...1233941312.jpg

Case Boat-tailed
http://forums.pelicanparts.com/uploa...1233941501.jpg

Preparing pistons (abrading crown for Ceramic TBC)
http://forums.pelicanparts.com/uploa...1233941791.jpg

Abrading (sand blasting back sides) increasing surface area for cooling.
Pistons will be weight adjusted by this method after TBC applied to crowns to insure all pistons are within weight spec.

http://forums.pelicanparts.com/uploa...1233942200.jpg

All critical areas are taped off
http://forums.pelicanparts.com/uploa...1233942291.jpg

Then blasted

http://forums.pelicanparts.com/uploa...1233942351.jpg

A few more Photos, sorry about the quality.

Please no worries, I'm anal when it comes to cleaning internal parts. The pistons will be, blown with 175 psi of compressed air between careful cleaning with a stiff tooth brush, then put in the dishwasher for a couple of wash cycles (when the Miss's is not home) to insure any imbedded sand is released, before assembly.

http://forums.pelicanparts.com/uploa...1233943023.jpg

Shot of ports clean up of casting imperfections.

http://forums.pelicanparts.com/uploa...1233943133.jpg

DIY valve guides: Reaming the guides to size.

http://forums.pelicanparts.com/uploa...1233943301.jpg

Checking guide to valve seat concentricity.

http://forums.pelicanparts.com/uploa...1233943415.jpg

Hey it fits and no more wobble.

http://forums.pelicanparts.com/uploa...1233943464.jpg

Another shot of the intake port after clean up, Labor of Love doing that job.
http://forums.pelicanparts.com/uploa...1233943950.jpg

Enjoy, thanks for your interest's and feedback on my build.

I will post more as they come, and hopefully they will better quality.:)

WOw this is kewl!!
Good job on the sand blasting.
Ok I am trying to keep a shopping list here..
You put new valve guides in?
And the chrome headers Rock! http://forums.pelicanparts.com/suppo...leys/2ar15.gif[img]

Yes put in my own guides, installed first oversize, purchased from our Host.

I went to 2 local shops, no one in the area had the tooling or any Porsche experience. After hearing of shipping nightmare stories and heads destroyed I did not want to chance shipping them. So in the end I worked an arrangement with a shop were they would grind the valves and seats for me but I would R&R the guides.
Figured the cost of the reamer and pilot works out to be about the same as the shipping would of been anyway. Besides I'm a hands on guy that likes to get into everything. This also allowed me to clean up the ports while the guides were out. I decide I wanted to try out some coatings in my build so I'm going to Ceramic coat the combustion chambers and exhaust port prier to reassembly.

More photos

Piston taped up ready for application of Ceramic coating, note large black O ring used to seal off top ring grove.

http://forums.pelicanparts.com/uploa...1234830882.jpg


and here we have a fresh batch of Coated pistons Hot out of the Oven
(they were post cured at 350deg/f for 1hour and gradually cooled before taken out.
I picked up a used stove from our local salvage yard and hooked it up in the garage.


http://forums.pelicanparts.com/uploa...1234831294.jpg

Hot out of the oven, oh they look so good.

http://forums.pelicanparts.com/uploa...1234831405.jpg