i posted this up over on performance trucks. some specs on my curent set up.

twin gts70's. eldebrock intake, 90mm tb, meth, decent sized intecooler, locked 4l80e, thru tcase, 595/590 234/232 115+1 cam, stock lifters, 921 springs, 408 with afr225's, 8.7-1 cr.

i am a little disapointed. not really sure what is going on. either i have some issue i am not aware of or the intake didn't do much and even hurt power for most of the run. in my mind the intake design on a boosted set up should be as open and strait to the head as you can be, it seems like runner length shouldn't matter when you are pushing the air into the cylinder but from my charts it looks as if i lost a fair amont of low end in favor of a slight amount of top end. if i had a solid valve train then i think i could take the rpms up to 7000rpm and see some nice gains up top but with a hydrolic set up the high rpms are not there. valve float kicks in about 6500 and even sooner with the high boost. the chart below is about 13psi, both runs are with the twins and closed exhaust. run1 is the stock intake and run 13 is the eldebrock intake. there is one thing i didn't think about at the dyno. the stock intake was with pump gas and the new intake was with race fuel and i never tried adjusting the timing. from what i have been told race fuel needs a little more timing due to the slower burn rate? that probably would have made up some of the diference.



the high boost hp numbers are interesting. there is some good news and probably some et gains to be had with the twins/intake. this next set of graphs compares the single with stock intake(run 16) to the twins with the eldebrock intake(run 24). both runs are with open exhaust and race fuel.

while turning it up we tried adding some timing and it perked up prety good going from 13 to 16deg. we didn't try any more timing than that. we probably should have just to see what it did. during a run down the track most of my time is spent above 5400rpm so you can see where i should pick up some et at this boost level. the twins seems to really hold the boost well and react well to the boost controler adjustments. we turned it up one run higher than the one posted below, more like 25psi and it had a peek of 1021hp but the hp was lower in the higher rpms. i believe it is hiting valve float at that boost level.



with the hydrolic cam i think i will keep the boost down around 22-23psi max and if i dont hit my goal at that boost level then add a little more timing and see if it picks up any et. i nearly hit my goal of 9.99 with the single and there is close to an extra 100hp up in the rpms where i will be for most of the run so i see a 9.xx as a real posiablity. i think for the twins and intake to really shine i would need a solid roller and run this thing up to 7000rpm along with some even higher boost. without the solid roller i think i would be better off with some smaller turbos.

something to mention. for some reason with the twins and intake it runs and drives better than it ever has. at the track the big single would actualy build tq too fast down low. not instant, it still needed some nitrous but once it started to build boost i couldn't turn it low enough to avoid wheel spin. now with the twins it seems to bring the power on at a rate that works well. i made 6 runs over 1000rwhp.

last trip to the track i was running out of fuel. since then i plumbed my fuel rails in parallel and hooked up a boost a pump running my pumps at 17volts. on the dyno it held fuel presure so i am ready to try the track again. maybe next saturday if i can find a track with an open test and tune. damn 9's are kicking my ***!

 

Congrats.... very nice results.

By the way...Did Cmotorsport build your engine? Which one did you go with?

 

sweet. I'm building some logs like you made. Shouldn't be a problem for me then. Congrats. You'll see the 9s soon.

 

Im sure your 9sec dreamer title will be gone soon. You should PM worm boy or call LME for the springs they use on there high boost LS engines. Just a tought! Those are some sick numbers!


JMG

 

Looks good,your issue is the tune.Timing and A/F has to be changed with the intake. We even saw a good gain switching to that on a boosted 4.8l motor--everywhere.

 

that is awesome

 

Nice numbers.

I spin my hydr. motor to 7800 with no valve float. That's at 27+ psi and with more timing than your running. When we ran the 921 springs they had to be shimmed to get enough seat and open pressure. I'm now running a dual gold spring that TEA uses. No shimming needed.
Another issue might be the stock lifters. There not designed for high rpm and high spring pressure (boost). They might be bleading down. We were told that they could collapse in these conditions. I run Morels right now.

Good Luck.

 

i wont have money to buy any parts for awhile so going with the parts i currently have i guess i should mess with the tune.

considering i have 114octane fuel what timing should i be looking at?


cmotorsports did build my motor but they closed their doors.

 

You run 114 with meth?
I run 116 only now and have run up to 21* @ 27psi. This equals a lot of cylinder pressure and I do push water.

 

95% of the time i run pump gas and meth. thats good for 800-900hp and mid 10's all day long. now i am trying to push it into the 9's so i put in the race fuel. i dont think my fuel system is capable of feeding the motor all the fuel it needs without the meth and i am not ready to spend the money of a killer fuel system so i am leaving the meth on.

does anyone think the meth is hurting power?

 

1000rwhp is a lot of power you should run 9's with room to spare.

 

5000+lb's is a lot of weight. i would be happier at 1100rwhp. i am starting to think with the race fuel my timing might be too low. that 1012hp run was 16deg max. my fuel map could use a little more work too. i didn't have time to really dial in it that day.

 

Tune....

HEy, just say something in a mag the other day. Its a big bag that you "Bolt" down in the bed to get more rear traction. HAve you seen it? Dude, im sure!!! Anyways, you have the power. I agree your timing could be bumped up a bit more and your fuel A/R seems fine. What fuel pressure are you seeing at your higher boost runs?

MAybe now instead of focusing on power, get that twins setup hooking and digging in, i feel you have the power to getthe 9.99, just needs a bit more seat time i guess..

congrates!! You think a twins kit like that would fit in a H2? Buhahahha!!

 

Parish... just glad to see you back here again. Its been a while. Your truck is still a monster I see.

 

I'm no expert but, don't the 70's seem big? I always thought 66 or 67's would be a nice balance for a 408. Just my $.02 Think that would be easier solution than going solid.
Time for dreams to become reality
Good luck parish8.......truck is already freaking sick!!

 

I wouldn't use those calculators to base anything off of. I put in 3710 weight. 171mph trap. And got 1448rwhp and 1708fwhp.

I think you def. need more timing. I ran 104 octane with meth at 21* with no problems. Well, besides pushing water. At this level, as you found out a couple degrees of timing can make a big difference. I think a 9 is in the bag though.

 

70's are fine, just need some timing and little tuning help. With the right converter you should be golden. You have a transbrake and a 2 step yet?

 

i have a tight converter, no tranz brake or 2 step. it is still a street truck, i am just trying to get my 9sec pass. spraying it off the line gets it moving just fine. i seem to be able to cut prety consistant 1.5x 60'. thats with quite a few stock parts under the truck and no suspension work. if anything i might try a set of caltracs but i dont want to hit it much harder off the line without some beefed up parts.

those calculators have been very acurate for me.

i think i will hit up the dyno one more time before i goto the track. try a little more timing and work on that fuel map. the local dyno is soo cheap i might as well take advantage of it.

 

Did I just read both of these in the same post?!

 

it is prety durable, i am not disapointed with that part of it.

last year it just barely broke the 1000rwhp mark. since then i have done the twins, larger intercooler, intake and larger tb. a significant amont of work and didn't pick up any power. just shifted it a little higher in the rpm band.

last year with the single i never switched over to race fuel. pump gas and meth got me to 1000rwhp on the dyno. this year i showed up at the dyno with strait race gas. i didn't change the timing much, maybe the slower burning fuel is killing my power and it just needs more timing to rock?

i am a little more prepard with what i want to try the next trip to the dyno. there might be a few more hp left in it without changing out a bunch of valve train parts.