# Orr89rocz's 1989 Camaro Iroc-z 5.7L **URL:** \ **Category:** Builds\ **Created:** [March 12, 2007, 9:09pm UTC](https://forums.speedlife.net/t/orr89roczs-1989-camaro-iroc-z-5-7l/188547 "2007-03-12T21:09:21Z")\ **Posts on this page:** 1\ **Showing post:** 658
**Author:** ![Quik](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/quik/32/5979_2.png) [@Quik](https://forums.speedlife.net/u/Quik)\ **Post date:** [December 22, 2009, 9:09am UTC](https://forums.speedlife.net/t/orr89roczs-1989-camaro-iroc-z-5-7l/188547/658 "2009-12-22T09:09:05Z")
> [@Classified Section Feedback - For People Who've Used It Only](https://forums.speedlife.net/t/classified-section-feedback-for-people-whove-used-it-only/41846/17): > > Well there are no maps for these master powers but I compared them to a similar wheel size garrett and I am in the right range for the power numbers I want. Granted the garretts probably use more efficient/higher flowing wheels even tho they are the same size. > > I shall try the .96 housings and if this doesnt change my top end, then I may have a problem with the cam/valvetrain but I dont believe thats the issue. > > i dont see why these turbos cant support 400whp a piece… i saw 690whp with a crap rich tune with issues with backpressure I think and a converter that isnt working right. 800whp is where i want to be ultimately. I trap 141 with 650whp. 800 puts me near 150 i think, probably higher and thats close to an 8 second car 🙂 > > You seen how my converter flashed sooo high. Its way too loose so i have no idea what “rpm” full spool is, but just look at the dyno vid again and think back to that day… Full throttle hit and it was spooled in a second since the converter flashed and he did start the run at a lower mph speed so the initial rpm was low. If i had a manual, i’d guess full spool would be around 3000 rpm or so which is where i wanted it. > > Do have 2.5" discharge. BUT i do have 3" single inlet. I MAY need to change that to a larger pipe, that may be a cause of my backpressure. Working the 60mm wheels too hard and having to pump through that small 3" pipe. More than likely I’ll replace the inlet pipe and throttlebody before i do the housings but not sure. Maybe do it all at the same time. > > Either way the cam should go to 5800 rpm. Similar cam in a 369 sbc pulled to 6500 rpm peak hp. My 401 will swallow that cam and should peak 5800. I think i saw peak hp at 5200-5300 rpm and it carried abit then fell off. If its backpressure issues i can see why it didnt pull higher. Hope to get turbine housings and with my dual 3" exhaust now, hope to see higher rpm. > > But then again not sure how accurate the dyno numbers/rpms are. Converter may have hid true peak rpm, but tq/hp cross on the graph is 5252 rpm and thats where my peak was. Hard to say sooo many variables. So much needs replaced give you an example of how that backpressure will kill a cam’s range. the ls6 cam which seems to be very popular pulls na till about 6200 but in every boost setup ive seen ti starts to choke at 5500 and drops badly at 5800. sorta what yours is doing. more duration would allow you to pull much higher. im kicking idea of going from 2.5 off the discharge to 3" charge pipes instantly and then of course going 4" to the tb. this should create less IATs and allow the spool range carry little further. i do plan to do dual 3" with these turbos i know i can fit 4" dp on the one side but doubt i can do that on driverside, however i may even do 3.5 but will see. going to see if i can step up to a large AR. should be interesting with a 3200 stall and 410s. heres a thought if you have time to do this. get another boost guage mount it in the IC before the core then take reading at intake for other reference. see how much drop you are seeing. if you see more then i think 2psi drop that can also be causing your power range loss. some say your dual 3 into single 4 is causing you issues but then others say its fine. changing it out cant hurt and can only help. simple solution would of been toss cut outs on the DPs. --- _[View the full topic](https://forums.speedlife.net/t/orr89roczs-1989-camaro-iroc-z-5-7l/188547)._