Okay I know there are some really smart procharger guys here but everytime I post for help I never get any so i will ask this PLEASE help me Im about to sell the dam car! Okay I had a 346 stock bottom end with patriot stage 2 LS6 heads and 224 581 114 cam, 10.9 to 1 compession 2bar tune and D1SC with the 4.25 pulley making 632rwhp at 6600 rpms, ran good all fine and dandy well had a mishap and then needed a change so I ordered a iron block forged 408 with diamond pistons, proselect diamond rings, clevlite H bearings, ARP throughout, cometic 51 MLS head gaskets, rollmaster timing chain, LS6 pump, LS6 intake stock TB, same 224 cam and lifters, and AFR 225 72 heads, with 10cc pistons come out to about 9.7 to 1 comp. I kept the 4.25 pulley on the D1SC and broke it in nicely for about 500 miles and then did some dyno loading and afr tuning to break it in even better for another 200 miles and then let er rip and it made about 6psi till 6500 okay that felt great and made 615rwhp untuned but ALOT more down low and in the midrange. So then I decided to swap on the 3.4 pulley and got 10psi till 6200 then boost started to fall off but made 627 at 6000 and a CRAP load more down low it gave me 5-6 psi right at 2500 felt almost like a darn turbo I love it. But heres where my problem lies I have checked all my connections, I have checked the bypass, the blower keyway, changed ATI crank pulleys, changed belts and everything and for some reason it will not boost past 7-8 now and for a while it would start falling off after 5000 rpms to about 4-5 psi Im lost ive checked everything the car still pulls hard but the boost is going away. I cant see any belt dust and it is REALLY tight I thought maybe my heads were leaking but car runs great and no leakage anywhere, then got told it could be my springs but they are brand new AFRs and only 1000 miles on em with a baby cam and the car continues to pull so I cant see that being the prob either PLEASE HELP!!!! If someone can guide me the right way i swear i will send that person $100 just for the help and my post here will serve as the promise. The car still gives me 5-6 psi right off the bat it just doesnt continue to climb as it should this is an 8 rib set up ati balancer stock crank pully size I think its 7.25 and the blower pulley is 3.4 I love how fast the boost comes on that why i have not changed my pulley.

 

the stock ati pulley with that kit is 7.65, with what your telling me your impeller speed is around 57195rpm. from what I hear around this site on a stock 8 rib you could have belt slip problems. my new setup will be pushing 62000rpm on the impeller so im buing a reichard racing blower pulley to help eliviate slipage. is it possible your cavitating the blower due to the stock inlet hat? have you watched all your plumming while doing a pull to see if any hoses are sucking shut? just a few ideas, good luck

 

Definately go with the reichard racing pully. I have a 402 with a f1-c sdce 8-rib and with the regular 3.7 pully i could only make 575hp on the dyno. Since then I swapped to the reichard racing 3.75 pully and put down 715hp. I really couldn't tell that my regular pully was slipping on the dyno besides the low power it made and a little belt dust. Definately check over your intake like lmt0705 said. Then check your impeller out Make sure that it's not loose. Well I hope this helps you find your problem soon. Good luck and don't give up.

 

Okay I will check into the richard racing pulley where do i get one??? So is the stock size of the ati 8 rib 7.65??? I have taken the hat off and even taken the housing off the impeller just to check it out looked perfect. I may try to go down to a 3.7 and see what that does. Thanks keep the ideas coming. Havent been able to watch the hoses as I am the one operating the dyno.

 

http://www.reichardracing.com I'm not sure about the ati one i run the sdce

 

good luck man sorry i dont have any info im a newbe

 

Thanks man and never be sorry for offering advice never know you may just know the answer

 

Chris, I'm assuming you checked out the bypass valve since I talked to you yesterday. I'd remove the intercoolers and pressure check them. It would help if you could have someone dyno the car while you look everything over. On my Mustang Dyno, we can set it up to simulate a mountain grade to put a load on the engine, so that we can keep it at a constant loading, which enables us to have the time to check for leaks.
Last but not least, it still could be the relatively new valvesprings, even though it is still revving up through the rpm band.

Sometimes these problems can be a real hassle to hunt down... Bob

 

yes im sure the stock crank pulley is 7.65 on the d1sc 8 rib f-body kit. max impeller speed is 62000 the formula is crank pulley/blower pulley times 4.10 times max motor rpm.

 

I'm thinking its a bypass valve issue. Letting boost slip by at higher rpms...are you checking it at WOT to make sure its completely closed not letting any boost escape?? Also IMHO get the SDCE set up. A little pricey but it WORKS!! Good luck and don't give up yet...

 

Okay I will keep checking stuff and see where it may be going I did take the bypass off and plug the line and between that and tightening the belt it seemed to help at least its not dropping boost as rpms rise now its just staying to a steady 7-8psi still not what i think it should be so I will see what a richard racing pulley and the SDCE can do for me but where would I even order the SDCE??? If Im doing the formula correctly then Im almost 60,000 rpms blower speed at 6500. A little to close to comfort for me I think i will slow it down some.

 

ADAM !!!!!! Sorry for the guys; Never seen this guy posting here before Adam, Dennis made a vid of you from the weekend at PAS here: https://ls1tech.com/forums/multimedia-exchange/649764-dyno-video-715hp-2002-firehawk.html

...sorry for the guys.

 

dammit i thought youd b helping haha

 

Thanks Frosty (Aka snowb11)

 

Have you put a new belt on it recently? Once they slip and get glazed up they are no good anymore. I wouldnt change pulleys, if you are only going to 6500 the 3.4 should be OK, I run my D1 at 62K at 7000rpm.

The reichard pulley will help IF thats what the problem is, the SDCE will eliminate all doubt if its the belt or not.

What kind of bypass are you running?

 

Im running the one that comes with the kit not to fond of it but cant find a better one to run any ideas there??

 

http://www.exoticperformanceplus.com....html?item=644
http://www.exoticperformanceplus.com....html?item=646
http://www.exoticperformanceplus.com....html?item=648

This is a really good bypass valve. Bob

 

Yes it is...! You can see it where we tied into the IC piping. BTW no longer running this filter set up...

 

dj what kind of intake is that ???? sry

 

Thanks Bob why didnt you tell me about this yesterday on the phone haha can it be used with the twins??? Do i just weld it in and done?? Let me know very interested

Ow and a HUGE thanks goes out to Bob, Brent, Jake, and everyone at EPP for putting up with all my calls and ???s as they have been always willing to listen and help me out TOP NOTCH SERVICE bar none!!!!!!!!!!! I am a lifetime customer and will continue to do buisness with them! highly recommend them for anything you need!

I am going to install the new longer push rods as Brent, tony Mamo and I went over how mine were and while they were not too long we did find they were quite short only took just over half turn to tighten and should be 1 to 2 turns for proper preload. Also going to install the 3.70 blower pulley as this was the one I wanted to go with originally and the 4.25 pulled all the way to redline beautifully 6500rpms and so i just want to experiment a little.

Thanks to everyone taking their time to help a fellow LS1 member out you guys rock