JUN Type 4 High cam. Does anyone here have tried this kind of set up?


S

skyR

skyR
Joined
Jun 20, 2007
Messages
85
Hello,

Does anyone have tried this before ? My set up gonna be as belows :

JUN Type 4 high cam set including valve spring & retainers
Piston size 83.5 with b18c block
Ogura clutch
Intake manifold - Skunk2 pro series
throttle body - stock b18c
stroker kits - stock b18c gsr
4.4 final drive
ECU tuning ( chrome )

Any comments and suggestions are welcome.:nice:
 
did you resleeve the block? How are you running a 83.5mm piston?

you don't mention what the compression ratio is...

and it's CROME. as in www.tuneitwithcrome.com

besides that..what are you expecting in terms of goals?
 
I just wanna know about the set up that I'm going to do soon. Is it recommended and gains 2++whp ?Please advise.
 
Some of us have some decent experience with the parts you listed above, but you don't quote anything in terms of compression ratio.

Obviously that will be important to the potential power gains. I can say - "Will running a 84mm piston be good with Jun cams?"

The answer is both yes and no...Yes if the compression ratio is above 11.5:1 and no, not that good if it's only at 10:1.

You don't say if the head will be ported. You also don't tell us what header you will be using. With cams this big, I would expect to make well over 240whp that's if you have all the proper bits working in harmony.
 
I think you need minimum 13CR. Those pistons are damn big!
 
RagingAngel said:
Some of us have some decent experience with the parts you listed above, but you don't quote anything in terms of compression ratio.

Obviously that will be important to the potential power gains. I can say - "Will running a 84mm piston be good with Jun cams?"

The answer is both yes and no...Yes if the compression ratio is above 11.5:1 and no, not that good if it's only at 10:1.

You don't say if the head will be ported. You also don't tell us what header you will be using. With cams this big, I would expect to make well over 240whp that's if you have all the proper bits working in harmony.
Click to expand...
thanks for the reply RagingAngel.
In term of compression ratio , i can say it is about 11:1 appx , the header is 4-2-1 spoon , ported head and I'm running with 5 zigen fireball all the way.Is it to big if I'm running with 83.5mm piston size ? OR using wiseco brand piston probably it may help a lot..
 
I have the Jun spec 4 on my race car. that the only one in Europe.

You will need minimum 13 to 1 CR, as the cam lift is so high, you will lose a lot of compression from the valve opening at the same time. Its very difficult to get this set up properly. I am rebuilding my engine again as now I am running about 13.4-1 CR to get this work. And the peak power is at 9800rpm.

You cant use wiseco with this set up, best to try CP.
 
Dixcelbrake said:
I have the Jun spec 4 on my race car. that the only one in Europe.

You will need minimum 13 to 1 CR, as the cam lift is so high, you will lose a lot of compression from the valve opening at the same time. Its very difficult to get this set up properly. I am rebuilding my engine again as now I am running about 13.4-1 CR to get this work. And the peak power is at 9800rpm.

You cant use wiseco with this set up, best to try CP.
Click to expand...

:nice: what he said!

SkyR,
Actually, I think tuning is the hardest part, at 13CR+ and Lumpy cams, your tuner will have to be damn good or it'll just be ****, like REAL ****. But if done right, it'd be really nice.

I suggest stg 2 cams, as these will need much less work to be done. your going to spend a fortune on stg4. but if you got the money, why not. lol

Yeh man, those pistons are F ing big! Stock CTR is 81.00mm, and resleaving is required for 81.25mm oversized pistons. lol
 
It's actually safe to run up to 82mm on stock sleeves for a mild build/rebuild. Anything bigger is really pushing it.

If you're going to re-sleeve, might as well run an 84mm piston or even something slightly larger than that. Don't forget to spot face the head.

Dixcelbrake, I'm wondering why you say it's not possible to run a Wiseco piston to make over 13:1 compression?
 
Is not too safe to run over 13-1 CR with stock sleeve. 81.5mm is about the max you can push.

Wiseco doesnt make any 85mm piston with high compression over 13-1. And also CP have better quality piston. I used to have Wiseco piston in my old engine but it leave a few mark on my block pretty bad.
 
That's really strange that you say the Wiseco isn't available in a compression ratio higher than 13:1 in an 85mm piston.

I guess the suppliers are different than in the states and the UK?

I'm looking at it right now:
-85mm piston
-87.2mm stroke
-5.433" rod length
-12.92-13.81:1 (this of course varies by deck height/head milling/types of valves/combination of all 3)
-8.4cc dome volume
-21.0mm pin diameter
-300/81 gm piston/pin weight
-1.180" compression height

What was your piston to wall clearance on your last build? We've had good luck with Wiseco, Arias and CP. Our choices are based off budget and sponsorship of course. But with that being said, all forged pistons are not created equal.
 
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