R34 Gtr Build

[bigmikespec]

Bobby, I am also interested in what John has to say with running such high compression and high boost. Obviously E85 makes it better but how much timing realistically would you be able to run with close to 10:1 static comp and 50psi boost?

What is the deck height and head gasket thickness?

[Nee-san]

Bobby, I am also interested in what John has to say with running such high compression and high boost. Obviously E85 makes it better but how much timing realistically would you be able to run with close to 10:1 static comp and 50psi boost?

What is the deck height and head gasket thickness?

I will let bobby answer for sure, but I would say modification of the combustion chamber and piston would allow this.

[bigmikespec]

Yes but from what Bobby has already mentioned the squish pads will be kept; I am sure the head is ported. I can't remember if oversize valves are being used too?

[BOBBYr34]

Hi all,

First 49psi Turbo side after the intercooler this will be 34psi.

The deck height info i will find out and let you know.

The head gasket thickness is 1mm.

We can run alot more advanced timing then any other normal engine.

Why is it we cant run advanced timing in other motors as that they start to detonate. Because they need so much fuel to keep the chamber cool and soon as you put more timing in then detonate. To avoid this problem you need the correct selection of cams and the correct lift we this is why we can run this high comp.

Head has standard valves with custom pistons and no chamber has been changed nor has the port been opened up. The key is squish you can run more timing and you can lean mixtures and minimise detonation.

John in tha past has tunned alot of V8 and tuned them to 14.1 AFR under load and still making power this is not heard of, any tunner will say that is too lean under load and will blow the motor.

I will still ask john the question i will have to record it on my phone the answer as he will not do a video 8(.

[BOBBYr34]

Just got confirmation Deck height is 7 thou with a 1mm headgasket.

[XRATED]

Wow this thread turned into somthing veery different than the first page...

People forgett that the last 10 or 15% of potential usually takes up 80% of the resources (time/money/material etc) to achieve. I'm diggin the process and I hope to see more of how things were calculated, planned, fabricated etc.

Also, the r and d that goes/wen't into most of the off the shelf products we buy to 'bolt on' had alot more than 10k invested before production- per piece!

Good luck and keep us posted!!

Cheers

Justin

[GTRNUR]

Just got confirmation Deck height is 7 thou with a 1mm headgasket.

I'd like to have a chat to your builder John about what he is doing with this setup. Ive read a lot about optimising the squish area of the combstion chambers, and specially designed "squishy" pistons that aim to compress the air fuel charge into the perfectly shaped combustion chamber and maintaining a high compression ratio at the same time. Like all hot-rodding idea's concepts arent new, but at the same time they arent common either as it takes time and skill to setup the engine properly.

The information I read about it was relating to SB Chev's and nascar in the 80's. To a degree the RB26 in stock form does apply some of the concepts, but in reality as a mass production engine they arent all perfect or 100% identical by any means. Most blocks have un-even deck heights from factory.

Im guessing that is a 7 thou positive deck, which will mean that with an un-compressible 1mm metal head gasket he is aiming for around 33 thou head to piston clearance which is about as close as anyone would dare. Especially when you factor in the big HP nature of the engine and that to do so you will be running much larger than stock clearences on the crank and rods. It will be interesting to see what kind of rods you use as well, because when things are setup with working clearances being this close, even thermal material expansion can ruin your day. Im thinking they will be titanium.

[BOBBYr34]

I'd like to have a chat to your builder John about what he is doing with this setup. Ive read a lot about optimising the squish area of the combstion chambers, and specially designed "squishy" pistons that aim to compress the air fuel charge into the perfectly shaped combustion chamber and maintaining a high compression ratio at the same time. Like all hot-rodding idea's concepts arent new, but at the same time they arent common either as it takes time and skill to setup the engine properly.

The information I read about it was relating to SB Chev's and nascar in the 80's. To a degree the RB26 in stock form does apply some of the concepts, but in reality as a mass production engine they arent all perfect or 100% identical by any means. Most blocks have un-even deck heights from factory.

Im guessing that is a 7 thou positive deck, which will mean that with an un-compressible 1mm metal head gasket he is aiming for around 33 thou head to piston clearance which is about as close as anyone would dare. Especially when you factor in the big HP nature of the engine and that to do so you will be running much larger than stock clearences on the crank and rods. It will be interesting to see what kind of rods you use as well, because when things are setup with working clearances being this close, even thermal material expansion can ruin your day. Im thinking they will be titanium.

Well you are more then welcome to speak to john however he does not speak to anyone on the phone, the only way you would be able to speak to him is in person and he has no problem in speaking to anyone face to face.

What you have said about the Nascars is correct squish applies to any piston motor even a 2 stroke john setup, my 2 stroke jet motor and let me tell you the thing is like no other with the squish closed up it makes more power then any other 2 stroke motor and uses less fuel then standard, the guy tuning it could not understand !!!.

Getting back the RB you are correct 7thou Positive Deack 1mm head gasket equates to 33thou piston to head clearance. Regarding the clearance for the rods and crank i will have to find out. The crank i am using is a Z-tune stroker crank with crower conrods.

[BOBBYr34]

Below is the vid i made explain some parts of the wastegate merge into the dump its hard to hear john sorry will try again!!!!!

[ylwgtr2]

Well you are more then welcome to speak to john however he does not speak to anyone on the phone, the only way you would be able to speak to him is in person and he has no problem in speaking to anyone face to face.

What you have said about the Nascars is correct squish applies to any piston motor even a 2 stroke john setup, my 2 stroke jet motor and let me tell you the thing is like no other with the squish closed up it makes more power then any other 2 stroke motor and uses less fuel then standard, the guy tuning it could not understand !!!.

Getting back the RB you are correct 7thou Positive Deack 1mm head gasket equates to 33thou piston to head clearance. Regarding the clearance for the rods and crank i will have to find out. The crank i am using is a Z-tune stroker crank with crower conrods.

the guy tuning it could not understand????????who was that?anyone that has half an idea with twostrokes knows that most if not all original squish bands on two strokes (even competition off the shelf high revving mx bikes)have an excessive squish from the factory.......one of the first things we did since i was a kid was bubble gum the piston crown on our brand new never started race bikes and tighten up the squish.....sometimes we welded the chamber and changed the angle/width.... the changes had dramatic effects on the lower end power/response.....generally the larger the engine the bigger gap they had/require for instance with say a kx80 engines we used around .7 and kx500/cr500 around 1mm this obviously has many variables such as which fuel is used....sometimes we had diffrent head/cylinder/chamber combo's for diffrent tracks.....nice job by the way.....good to see someone putting in attention to detail

Edited April 15, 2011 by ylwgtr2

[BOBBYr34]

the guy tuning it could not understand????????who was that?anyone that has half an idea with twostrokes knows that most if not all original squish bands on two strokes (even competition off the shelf high revving mx bikes)have an excessive squish from the factory.......one of the first things we did since i was a kid was bubble gum the piston crown on our brand new never started race bikes and tighten up the squish.....sometimes we welded the chamber and changed the angle/width.... the changes had dramatic effects on the lower end power/response.....generally the larger the engine the bigger gap they had/require for instance with say a kx80 engines we used around .7 and kx500/cr500 around 1mm this obviously has many variables such as which fuel is used....sometimes we had diffrent head/cylinder/chamber combo's for diffrent tracks.....nice job by the way.....good to see someone putting in attention to detail

This was on a waveblaster with a 800cc bore with the lot billet crank forged pistons billet head nd so on. Oh this is a 93 model design so its very old. The squish was like 1.1 mm huge john remade the cup's closed it down not sure what he closed it down. The guy tunning had build so many waveblasters and tunned many of them when he went to tune this one it used smaller jets then a standard ski. As you can see now the later design 2stroke have that close squish.

This ski could only be run on avgas previously now i can run it on 98RON its one crazy ski.

[ylwgtr2]

im not sure about marine stuff as we only play with dirt/road race bikes here....and there isnt a huge range of twostrokes anymore mainly KTM's and i dont work on those at all....of late we been trying to keep the twostrokes alive by fitting cr500/kx500 engines to the klx/kxf/crf

range...i say fu(k the whales.....save the two strokes!

[bigmikespec]

Bobby, can we see a finished piston ready to be assembled?

[BOBBYr34]

im not sure about marine stuff as we only play with dirt/road race bikes here....and there isnt a huge range of twostrokes anymore mainly KTM's and i dont work on those at all....of late we been trying to keep the twostrokes alive by fitting cr500/kx500 engines to the klx/kxf/crf

range...i say fu(k the whales.....save the two strokes!

Marine and boke not much difference i like to hear that your keeping something old alive um something to let you know i remember i guy who John knows he had a 500cc 2 stroke he currently hold the fastest land speed please dont quote me i think he raced his 2 stroke im trying to remember his name but yeah go the 2 stroke.

[BOBBYr34]

Bobby, can we see a finished piston ready to be assembled?

Ok will get some detailed pics of the piston

[ylwgtr2]

As you can see now the later design 2stroke have that close squish.

Marine and boke not much difference

there is when we dont have later designs!thats what i was getting at

[BOBBYr34]

Some more pic's of the boot. Dry sump tank and Surge tank

[r33_racer]

Very nice build. Fantastic engineering going into this. Loving it!

[BOBBYr34]

Below is a pic of the Fuel cooler. This is setup on the return line as we didnt want heated fuel to go back in to the surge tank.

Its very important that fuel temp is watched when using E85 as the expansion is 10 times greater then normal fuel. This can cause a dramatic change in the AFR, example if you tuned your car on a hot day now when you drive on a cold day, it will run lean. Now if you have tuned it on a cold day now on a hot day it will run rich. Basically your fuel pressure can vary.

[popinr33]

wow cant wait to see this finished!