Lower boost with head shim

[stephenpen]

How much will boost drop with a head shim and cam timing.

 

[TurboTime]

I'm told a couple lbs give or take depending on the turbo application

 

[stephenpen]

I bought this machine that just had the head shim done, timing set and a smaller top pulley installed. I was told it should run 7.5-10lbs this way. But its only hitting 5.6lbs. I did notice it was revving low at 9500rpm Would 1500rpm make a 2psi boost difference.

We have no snow left hear on Southern Ontario so I cant run it again till fall. I only had it out for 15 minutes then the secondary started sticking open.

 

[HURRICANE]

1500 rpm will raise your boost at least 1lb

 

[ScottyD]

was that the sled advertised on here for sale

 

[stephenpen]

Ya. I pickup it up in bracebridge Saturday

 

[kinger]

Yes you want 10,500 and your boost will come back. Try a new belt.

 

[stephenpen]

Whats the most boost I can run on pump gas with the head shim. I do all my riding on Ontario trails in low elevation

 

[quebecmoutainrider]

I run my stage 2 with 94 at 14psi. sea level..got 2230 on it and no issues..A/Fs idel 13-4..mid.12-9..WOT..12-5..12-8

 

[stephenpen]

Yes you want 10,500 and your boost will come back. Try a new belt.

What mpi pulleys are you running to get 10psi. Are the pulleys marked or do I have count the teeth. Can I unbolt the oil tank and leave the hoses attached to have a look? or does everything have to be disconnected.

 

[kinger]

You have to count the teeth I tun a 26/22 combo to get around 10-11 psi.

 

[stephenpen]

I talked to the previous owner about the blower pulleys. All he did was flip the stock pulleys. That gave him 10psi before the head shim.
How many teeth are stock on the stage one kit ?

 

[machzrobbie]

Usually its 26-24, or 25-23 to get 10#, both ratios are very close -flip them the other way and you're down around 6# on the stage 1