twin turbo help please

[02bigstrokin]

alright so i got my new motor going and i replaced my factory ihi charger with a s366/74 16ss. my big charger is a gt45f 78/87 flows 110lb/min, pretty much same as standard s480 without race cover according to nathan. so ive got a manual wastegate adjustment rod on the s300 and a tial on the big charger. well something is wrong somewhere because i cant get the big charger to see but 20-21 lbs boost when overall is only at around 50. the first time i got into hard in 5th with the converter locked it jumped to 60lbs and pulled hard but then i felt a hard "clunk" that felt like it came from the trans and ever since then it wont boost over 50. i can go all the way loose or all the way tight with the 300 w/g and completly block off the big one and nothing changes. also i now have robs tuning and i can flip between the race tune and tow tune and they both feel about the same and both make the exact same boost? wtf? ive checked for blown boots, cracks in hot pipe, turbo shaft play, everthing looks good. any suggestions? thanks

 

[DuramaxPowered]

but then i felt a hard "clunk" that felt like it came from the trans and ever since then it wont boost over 50.

Are you sure that something in the trans isn't slipping? Turbos spool better under load and if the trans isn't loading the motor down that could be where you're problem lies.

 

[02bigstrokin]

no im not sure, it feels fine but i also got a p0742 code "range shift inhibited". but that was not on the same day. i cleared that code and it hasnt come back yet. my deal is i dont understand why i cant get anything to change with the big charger. no matter what tune, no matter what setting on the w/g it stays the same. when i had the ihi on there i could get it to range from lesss then 20 to over 30 by adjusting the w/g.

 

[wikdlmm]

Does it shake at idle in gear with foot on the brake..

 

[DuramaxPowered]

When you say "block off" the Tial on the big turbo, I assume that you are unhooking the boost line to the wastegate? Is it a 2-port WG? If not, you may need to swap a heavier spring into the Tial because you could be pushing the WG open just from exhaust back pressure. If you have a 2 port WG, put full boost to the top side of the WG and nothing on the bottom and that will hold it fully shut.

 

[NWTDIESEL]

It has to be the trans, your motor runs, idles just fine right?

Good luck on getting it figured out.

 

[McRat]

Check your riser pipes.

 

[02bigstrokin]

When you say "block off" the Tial on the big turbo, I assume that you are unhooking the boost line to the wastegate? Is it a 2-port WG? If not, you may need to swap a heavier spring into the Tial because you could be pushing the WG open just from exhaust back pressure. If you have a 2 port WG, put full boost to the top side of the WG and nothing on the bottom and that will hold it fully shut.

we actually took the w/g off and made steel plates to bolt in its place. but before we had it off thats what had it set to.

 

[02bigstrokin]

Does it shake at idle in gear with foot on the brake..

no it idles and runs fine.

 

[02bigstrokin]

It has to be the trans, your motor runs, idles just fine right?

Good luck on getting it figured out.

it doesnt feel like its slipping? it pulls hard it just doesnt make the boost it should and i dont understand why i cant change any of the numbers around on the big charger.

 

[02bigstrokin]

Check your riser pipes.

for what cracks? in the bellows?

 

[bigbird]

If everything seems correct other than boost is low, It's either wastegate setting or pressure is getting out somewhere.

 

[TrentNell]

The only thing that can slip in the trans with out codeing is the Torque Converter , if you worried log TCC slip . I would really look over the exhaust side from the headers out for leaks and check for boost leaks . Since you have the bottom turbo's gate blocked off it cant be that , Your top turbo flows more than mine , i would think it would be over driving to secound turbo not vise versa . You will get it figured out , call me if ya need any help .

 

[02bigstrokin]

so we got some logs today, and figured out what the "clunk" is. its me falling off rail pressure so bad with the 60's and single stock pump. i put the tune back in that i originally saw 60lbs on and it was commading 26k and holding about 10K this is not robs tuning, its an old tune. travis seems to think im never getting over the big charger. oh well i guess it is what it is. I need dual fuelers bad.

 

[S Phinney]

Have you dropped your fuel tank and cleaned the pick-up and sending unit housing? There could be some black algae growing that is restricting your supply.

 

[02bigstrokin]

no i havent, i need to install my draw straw i still havent done that.

 

[S Phinney]

You can drop the tank , clean and install a billet pick-up in about 2.5 to 3 hours. I'm sure it will help your problem out some.

 

[02bigstrokin]

yeah i going to do the draw straw soon, ive just been real busy building the motor and all.

 

[DuramaxPowered]

What makes it clunk when it loses rail pressure? Does the power fall off so quick that it actually unloads the power off of the driveline?

 

[02bigstrokin]

im not sure but it does it everytime. travis knew what it was before we even logged it. something defuels hard or something. it feels horrible.