I have a 93 cummins with a stock turbo cold air intake 4inch exhaust and the fuel screw half a turn from runaway. My problem is that when i'm accelerating in fifth gear from like 40mph to 55 mph or so the turbo will sort of surge and i watch my boost gauge jump from about 14psi to 21psi. Any suggestions on a better turbo or any solutions? Any help is much appreciated.

 

Sticky wastegate, and or actuator? Could be defueling bc of low fuel pressure, or gov spring.


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Its turbo surge. The turbo is trying to force more air into the engine than it needs. The noise you hear is the air going backwards through the cold side. A 60mm upgrade will cure that or a bigger turbo.

 

Turbo surge would be correct if he were getting off the throttle suddenly when this happened and boost spiked, if it's constant throttle something else is going on.


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Definitely not a sticky wastegate.... it's a stock turbo.

There are a lot of 'better' turbo's out there. For you, a smaller turbine housing would be better. 12cm2/14cm2 would be good. S300's and HE351CW's are popular these days, but even an HX35 off of a 2nd gen will be an improvement. A turbo works off of heat, produced by burning fuel. Hot gasses like to expand, which creates flow across the turbine blades. I'd say what's happening is your engine is lugging a little bit when you roll on the throttle, and it's generating a lot of heat, thus spinning the turbine faster, and creating more boosted air than your engine needs at that rpm range. Try doing it in 4th and see what happens with the turbo. You might also try moving your star wheel back up a bit... or is it down... I can't remember.

 

Ok thanks guys. I was thinking of buying the 60mm upgrade too, should I still get that small of a housing?

 

By the time yuo buy all that you could almost have a nice aftermarket turbo that will be 100x better then you built up stocker.

Hell for teh same money you can find a nice used turbo.

 

x2. See thread above^^^. You should be able to get a good HX35 for $150 - $200. HE351's are running around $250 - $350 these days, and S300's somewhere around the $300 mark. The HX is a bolt on turbo, and although it has a smaller exhaust housing the compressor wheel is the same size as your stock one so an upgrade would be advisable, (unless it's already been done.) The other two are not direct bolt on's but have both smaller turbine housing for faster spool up and bigger compressor wheels for more air and cooler running temps.
There are other turbo's available for sure. But these ones have proven results and are relatively cheap and easy to find.

 

"The HX is a bolt on turbo"
No it's not it is 1.25 inches longer(due to the waste gate housing) and the downpipe could interfere with the air box. Right now a guy on comp d has a compressor upgrade and exhaust housing for cheaphttp://competitiondiesel.com/forums/showthread.php?t=115409Rocky DANG IT THAT LINK DIDN'T WORK BUTS IT'S THERE HE JUST LISTED IT

 

Does it do it if your in 4th and do the same thing?
What axle gears do you have?
I think your lugging it and it's induced turbo lag cause mine will do the same thing.