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Discussion Starter #1
I need a little advice.

I bought a turbo from TSI and installed it on my stock RZR 4, I added a boost gauge and a o2 sensor and gauge, it seams to run good, no knocks, it is supposed to be set at 6lbs of boost, but my boost gauge looks like around 7 at wide open throttle.
The fuel to air gets down to 11 or 10.9 at times. I am running 91 real gas (no ethanol) I took it out on the county road and got it up to 60mph or so, but i still had a little throttle left when I let off the gas, it did not hit the rev limiter, clutch felt good.

The reason I bought the a turbo for the RZR 4 was to keep up with my regular RZR in the dunes, and give my passengers a bit more of a thrill.

I feel like as far as horsepower goes that i am fine with 6 lbs of boost.

My question is this:
#1. Should I make any adjustments to the setting, is it running too lean?

#2. Should I run race fuel? will it be better or worse on the engine?

#3. If I need to run race fuel can I run Torco and if so how much,

#4. Is there a good substitute for Torco at a parts store?

#5 Do i need to pin and weld my crank at these Conservative settings, or is that really necessary?

Thanks for any and all advice, I sure do learn alot on this forum, thanks!!!
 

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it isn't too lean. the lower the AFR number the richer it is. if it goes above 12.5 I would consider tuning it.

with stock engine compression I think you are at the limit for boost without detonation.

a mix of race fuel or torco would add a safety factory.

all my experience is with a low compression engine and higher boost,, so maybe someone with stock compression will chime in and give more advice.

:ride:
 

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you are running way too rich! should be 12.5 with turbo. you are missing some good hp!
 

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11 is still too low, will not run right. might as well get it tuned correctly!
 

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Discussion Starter #6
Thanks everyone, my main concern is not blowing the engine, I will tune it to 12.5 A/F on wide open throttle and I am thinking about just buying 5 gallons of Torco so I will always have it, it should last me a year or so.

Any other suggestions?
 

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if you ever have a spare couple hundred bucks,, get forged low compression pistons.
It is a good upgrade and with the lower compression you wont have to worry about detonation on premium pump gas.
 

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Discussion Starter #9
if you ever have a spare couple hundred bucks,, get forged low compression pistons.
It is a good upgrade and with the lower compression you wont have to worry about detonation on premium pump gas.
Can I replace the pistons without taking out the engine, if so where can I buy some low compression pistons?
 

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yes you can.
You have to take off the head and the cylinder jugs, but it isn't too difficult since it is a push rod engine with no overhead cam to deal with.

I got my pistons from MCX. They were made by JE.
Any of the turbo vendors on the forum can get them for you.



The stockers:

 

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if you ever have a spare couple hundred bucks,, get forged low compression pistons.
It is a good upgrade and with the lower compression you wont have to worry about detonation on premium pump gas.
I guess I should clarify this... you won't have to worry depending on how much boost you run.
even with low compression pistons you can have detonation if you turn up the boost too much.
 

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Discussion Starter #12
if you ever have a spare couple hundred bucks,, get forged low compression pistons.
It is a good upgrade and with the lower compression you wont have to worry about detonation on premium pump gas.
I guess I should clarify this... you won't have to worry depending on how much boost you run.
even with low compression pistons you can have detonation if you turn up the boost too much.
Got it, that makes sense. Thanks Again.
 

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That air fuel is not that bad...better to be rich than to be lean! And yes..the leaner you run the more power you make...but with a stock engine I think you are not too shabby...

Also did you go to a cooler set of spark plugs? This will help you with the heat!
 

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Discussion Starter #14
That air fuel is not that bad...better to be rich than to be lean! And yes..the leaner you run the more power you make...but with a stock engine I think you are not too shabby...

Also did you go to a cooler set of spark plugs? This will help you with the heat!
Thanks, how do i get "cooler" spark plugs?
 

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I personally think above 5.5psi on the "S" motor your reliability can start taking a nose dive. Torco is a good additive. Mix to 97 octane, stay below 6 psi, and keep the rpms at stock and I think you'll be ok. Now if you end up going with the low compression pistons, which is a good idea, you can progressively raise the boost depending on what low compression pistons you go for. For the most part, the component to watch out for the crank. Low compression pistons and revs below 6500 seem to be your biggest insurance. Not sure on the plugs, I would like someone to chime in on that as I would like to know aswell.
 
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The coolest heat range plug you can run without fouling or missing on a boosted application is generally the best. Hotter plugs mean possible sources of preignition/detontation..ie fuel mixture igniting prior to spark ignition. The cooler the plug the less chance of this being caused by a hot spot on a plug..
I haven't yet reseached a cooler plug for this application to run with boost..but I will be SOON. Lower compression pistons help with this alot..even so IMO 1/2-1 heat range cooler would be a good idea..JMO..defnitely on stock S compression..would be a good idea.
Oddly though..the issue doesn't seem to be with the pistons from what I have seen it is the crank...the cooler heat range isn't going to help the crank really..yes detonation is hard on the crank...but it is much harder on the pistons..if that were an issue(ie stock plug heat range) we'd hear more about burnt pistons....it's nasty what it will do to the top of a piston..looks like someone took a blow torch to the pistons..
So while it wouldn'd be a bad idea as long as the engine runs ok..in this application I doubt it will keep the motor together if the crank is going to give up before the pistons...
 
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the ring lands are the weak link on the stock pistons:

Good point...the ring lands aren't actually weak..that is likely from ring gaps too tight for a boosted application and the ring tips butting....not much will help that in a boosted application..except opening the ring gaps..and if you go to the trouble to do that you might as well put in more appropriate CR pistons. JMO
 

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Discussion Starter #19
That air fuel is not that bad...better to be rich than to be lean! And yes..the leaner you run the more power you make...but with a stock engine I think you are not too shabby...

Also did you go to a cooler set of spark plugs? This will help you with the heat!
Hey 358ciHD,

I see you have a Rzr4 with a turbo, what clutch are you using, I am having problems finding the right one for a rzr4 with turbo.

Thanks
 
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That air fuel is not that bad...better to be rich than to be lean! And yes..the leaner you run the more power you make...but with a stock engine I think you are not too shabby...

Also did you go to a cooler set of spark plugs? This will help you with the heat!
Hey 358ciHD,

I see you have a Rzr4 with a turbo, what clutch are you using, I am having problems finding the right one for a rzr4 with turbo.

Thanks
I'm not trying to answer for 358ciHD..but I have a turbo on my 4..I'm running the stock clutches with STM adjustable arms/weights and ..there are a few spring combos you can run depending on your preferences...I got my set up with my Turbo kit from K&T Performance..
 
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