Nytro, head shim versus no head shim questions

redbull660 · May 26, 2008

I am going to put a turbo on my 2008 nytro this summer. The problem I am running into is do I really want to tear apart a perfectly good engine to install a head shim. Threw the research I have done, the only reason to install a head shim is to lower compression so a person can run pump gas without adding race fuel.

Wouldnt it be safe to run like 12 pounds of boost and run 50/50 pump gas and race fuel along with a air fuel gauge. I know alot of people out there want to MOST horsepower they can get which is cool but I think I would be satisfied with around 200 to 230 horse running a 50/50 fuel mixture. Is this a safe combination.

Sorry if this has been discussed before but I will be new to the turbo thing. thanks

M5- · May 26, 2008

I'm a believer in the head shim. It's not that big a deal to put it in and it'll pay for itself in like 2 days. Eventually you'll want to go over 12 lbs and the whole race fuel thing gets old pretty fast IMO.

M5

ridehard1212 · May 26, 2008

8-10lbs Is In That Power Range And Pump Gas Should Be Good.. We Run 94 Out Of Our Pumps, Im Not Exactly Sure What Thats Good For But I Think That When Guys Talk Pump Gas They Are Refering To 91..

I Would Also Think That With No Head Shim The Sled Should Be A Little Bit More Responsive???

Motleyone · May 26, 2008

My 2 cents

Do the Head Shim from the start so you do not have to go back in and remover everything to get back at it again. Do your cam timing and head shim at the very beginning of your install (totallyamaha.com has some really good info on this stuff). Pull all motor mount bolts and lift the engine up as far as it will go, if you do not you will not have enough clearance to get the timimg chain tensioner out and back in. It is a bit tricky but very doable.

If you do go with the head shim do not split your head gasket and put half on each side of the shim. This causes more hassle and problems than it is worth. Buy 2 new STOCK head gaskets and put one on each side of your shim (do not put anything on them, put em on dry). With the Shim I have in this has lowered my compression to 8.8:1. I should be safe up to 12-15 lbs and pump gas all day long although for saftey I will run 50/50 on days I want to run 15 lbs of boost. Anything above that and I would go with upgraded Carillo Rods and JE Pistons.

I am not expert by any stretch but I have done alot of research and testing (lol). I went with the split head gasket and copper coating and exaust gases blew through it almost immediately and caused me 4 weeks of headache. Sled of course would over heat instantly once I hit boost.

What kit have you decided to go with? Good luck with your install.

redbull660 · May 26, 2008

I am still up in the air on which kit to buy, I know the NW turbo works is the cheapest, it runs 8 to 9 pounds of boost and gives an honest 190 horse on 91 octane fuel. They did tell me that I can up the boost on this kit but would have to run race fuel mixed with 91 octane fuel.

I am also planning of putting a lite weight rear suspension on so that will help with only 190 horse.

M5- · May 26, 2008

Before I had a turbo I ran Nos. a 60 horse shot that actually dynoed at 58 horse. That put me around 185-190 horse on the juice. It seemed awesome at the time but now that I've got 250+ hp the 190 seems lame. I think it's pretty near impossible not to turn up the boost. 12lbs and up seems to be the sweet spot for most guys.

M5

mattymac · May 26, 2008

I rode JSCC's turbo nytro at 14lbs and no head shim, I think he was runnin straigt 110 or 112? Really responsive on the bottom!

If your gunna stick with low boost like 12 and under I think runnin the shim isnt worth messing with, sure its a good idea and cheap insurance but lower boost levels, all it will do is loose bottom end. If you have good fuel and dont mind paying for it, dont run it.

redbull660 · May 26, 2008

I will keep that in mind about the running that fuel.

euge · May 26, 2008

mattymac said:
I rode JSCC's turbo nytro at 14lbs and no head shim, I think he was runnin straigt 110 or 112? Really responsive on the bottom!

If your gunna stick with low boost like 12 and under I think runnin the shim isnt worth messing with, sure its a good idea and cheap insurance but lower boost levels, all it will do is loose bottom end. If you have good fuel and dont mind paying for it, dont run it.

What elevation was this? trying to figure out how low off elevation and at what boost I can go?stock motor-no headshim
2000Ft @ 110 octane, no headshim 14lbs? 15lbs?

mattymac · May 26, 2008

euge said:
What elevation was this? trying to figure out how low off elevation and at what boost I can go?stock motor-no headshim
2000Ft @ 110 octane, no headshim 14lbs? 15lbs?

Yeah I did forget to say that it was at fairview, 10K feet.

SNOW JW · May 26, 2008

Last I talked to him he and others were running 12lbs on 100% Av gas at about 6,000ft and above but maybe I'm wrong.

JSCC · May 26, 2008

No, you are right, as is mattymac. Normally we run straight av for 12lbs of boost. 6500' +.
We were tuning in for the drags when mattymac rode it at Fairview. We were running straight 112 just for the insurance up to 15lbs.

I have never ridden below 6000', so I cannot comment on what the head shim does down there. But above that, I will take the lower boost level with stock compression over the lost response and higher boost any day.

IRONMAN · May 26, 2008

If all you want is that 230hp range go with stock comp, you will love the extra response you will have. It is even noticable on a front mount which already has great response. I dont think I would go over 10lbs of boost though with a 50/50 mix JMO, unless you are always up over 6000'.

A buddy ran stock comp up to 15 lbs of boost, it worked awsome!! Straight C116 there was no sign of detonation when the motor came apart for pistons and rods. Had a head gasket fail as has happend to alot of nitros when they crank up the hp.

redbull660 · May 26, 2008

IRONMAN said:
If all you want is that 230hp range go with stock comp, you will love the extra response you will have. It is even noticable on a front mount which already has great response. I dont think I would go over 10lbs of boost though with a 50/50 mix JMO, unless you are always up over 6000'.

A buddy ran stock comp up to 15 lbs of boost, it worked awsome!! Straight C116 there was no sign of detonation when the motor came apart for pistons and rods. Had a head gasket fail as has happend to alot of nitros when they crank up the hp.

I ride between 8000 and 10000 feet elevation. So stock compression should be fine I hope thanks

snowy1 · May 26, 2008

if you add boost you need to retork the head or it will leak at some point,

powderlites · May 27, 2008

Head Spacer/No head spacer?

Cylinder pressure is what gives you throttle response.
Cam timing and Ignition timing alone can make a big difference on throttle response.
Lower the compression and increase timing and get the same response.
Having the perfect tuning for what your doing is the trick in making reliable power.
As for Ironman saying our rearmount turbo is the same as MC not really the same kit.
Extra injectors that just spray all at same time is not good for throttle response.
By adding 5 degrees advance in bottom end makes a rear mount come alive and hope some of the guys with RB3 on rear mounts can throw in there 2 cents worth on the changes to there ride.
Turbo's can make a big difference when using right A/R's with intake/exhaust work.
http://www.powderlites.com

Need for Speed 2 · May 27, 2008

Definitely do a shim. The nytro is a diferent animal. It doesnt take the heat well. With a shim and a rb3 controller your throttle response wont be an issue sore neck muscles from the snap. There is a learning curve on this nytro and the turbo builders are learning every day more about this 3 cylinder engine. Do yourself a favor do a shim you will end up there in the end. 15lbs of boost on pump fuel at sea level is what I run with an rb3 fuel controller 3.5 degreesin on the bottom 2.5 out at the top pulls like a mother.

Ak nitro · May 27, 2008

I went through this last october when I installed my Impulse kit. I did not want to tear into the head either. When I had it all apart I just decided to install the head shim anyway. I am glad I did to be able to run pump gas is nice too. I run an Impulse turbo so lag is not an issue, the throttle response is great for quick burst when dropping cornices and going through tight spots. I for one would not feel comfortable running over 10 or 12 lbs pump gas anywhere near sea level even with the head shim. I like to be running at least a/v gas when riding near sea level just for a piece of mind.

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Nytro, head shim versus no head shim questions

redbull660

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M5-

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ridehard1212

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Motleyone

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redbull660

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M5-

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mattymac

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redbull660

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euge

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mattymac

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