i have decided on running the pt 6776 dbb. which one exactly i have yet to decide. Ported shroud, 2.5 discharge or 3" discharge.
any opinions on this matter?
i currently have a t66 bb and she is only good for mid 10's
Its good for much faster than most think. Most on here arent even close to maximizing the turbo they have. Not you though. You have proved that with the PT54 and .63 ex housing . You have an anomaly with that combo. No ones ever came close to those numbers with that turbo. The 67 isnt going to take you much further than the 66. That is unless the turbo is an HPQ or GTQ. The 66 GTQ has been very low 10's. With the 76 trim exhaust wheel its being choked badly once mph is in the high 120's. I had a T72 with a 76 trim exhaust on the car before. Its picked up quite a bit of mph with the GTQ even though the comp wheel is 6mm smaller. Just proves the exhaust side needs the most attention.Out of curiosity, why is the 66mm only good for mid tens? Is it your altitude? I was always under the impression that they where low 10 second turbos.
The 6776 is just that a 76 trim exhaust (p-trim). Just what you have now. 67GTQ or HPQ is what id go for for if i wanted low 10's and high 9's at sea level. You need more comp wheel at altitude. The 6776 likes to be in the mid 20's also on a 231ci. The difference between a 6776 and a turbo like a 70GTQ is that you would run a larger cam and move the rpm band up some but still make the power at 25-28psi. 500whp at 20psi is going to need a 9.0:1 engine, a really efficient TC like the one i have, and a good tune. Assuming a 231ci. Theres no need to dyno the 2. Theres plenty of feedback on this site. A lot of guys have run the 70 GTQ (TSM) and many street guys have run the 6776. You average TSM engine goes about 140mph when run hard with a GTQ and most of the hardcore street guys go 126-128mph with a 6776. About 175 hp difference there. If the 6776 was run really hard and out of its efficiency range like the TSM guys run theirs it could probably go 133mph. So maybe 80-100hp difference. But remember the TSM guys are forced to run a tiny turbo. You can run anything you want. Your not losing a half sec. on a forced induction car at altitude either. Maybe a tenth or a little more. Dont let those guys fool you. A bigger comp wheel will eliminate all of those potential losses. Id go for the GTQ and a new 9.5 PTC converter myself.When i bought the car it vame from Rhode Island, so sea level, now the previous owner did one pull at the track and he did a 10:6 at 128. now the turbo is a turbonetics t66 with a single bb. it is also a p trim.
I have heard that a pt 6776 bdd (which i am assuming is a gtq) can touch the nine's. that is all i want.
even up at my elevation i liked the power of the turbo i had on there, but the typical rule i hear from the boys around town is that you should tack on 1/2 a second to you time slips from sea level. Now i just cannont live with myself knowing i have a 11 second car. no sir
Bison, you say that after the high 120 mph the turbo starts to crap out, but my worry here is if i go to a 70gtq, then i will have to run mid 20 psi to really start pushing out that power.
i want to put down 500hp to the wheels at around 20psi. that would be my street uniform, c16 and a whack load more boost at the track.
help.... So so very confused still.
i wounder if there would be anyone willing to do a heads up comparison between the gt 6776 and 70gtq on the dyno. i would be willing to use my new build motor, but i do not want to buy both turbos
what do i stand to loose if i go to a 70 gtq compared to a 6776? i know there are some things.
also, i am nearing the end of my budget, so i do not want to be spending too much more money to get this thing going. if i were to go to the 70 gtq, or hpq as the now call it, what type of cam would you recommend i run? currently i have a 212/212 full roller cam.
And since i have you around bison, i currently have a 3200 stall lock up converter from Eric Shurtz? what makes your converter better than mine? (i am not trying to be pompous, just want to know how they can differ.) aren't most people going with a 3400 for the dbb?
thank you soo much for your help it is making me think good and hard as to what i want to accomplish.
Adrian
Yes, it is true the tsm guys have gone low 9's with a 70 mm turbo but those cars are pretty much all out race cars turning some pretty big rpms, probably running 30-35 psi boost, mostly 245+ cu in strokers, and doing it under 1000 feet elevation. Besides, why run a smaller turbo you have to lean on as hard as possible to meet your goal, instead of going a little bigger so you can keep the boost down, if you don't have a class rule forcing you to. If Patrick says you need at least a 74 turbo at your altitude, I'd listen to him.
[Yes, I know a couple tsm cars see some steet miles and are only 235 cu in, but think how few of those there are and how many guys have blown up trying to run mid 9's in tsm.]
okay then, so if my thought process is working correctly, then if were to bump up my static compression, this will offset the stall of converter i would have to run? is that correct?
in this scenario, if i bump up the compression to 9.0:1 and run the 70gtq dbb could i run somethign like a 3200 converter.
Now how will a tighter converter effect my mph at the track? will a tighter converter take away from my et's or will it allow room for higher ones?
or would a 9.0:1 compression and a 3400 be better?
I've been following this thread with great interest. It's interesting that the majority of responses are talking about turbo size and construction and although very important, there's much more to running a 9 second timeslip than a bigger turbo. My experience tells me that most average turbo racers aren't seeing the maximum that their existing turbo (whatever size ) can deliver !
Adrian is wanting to run a 9 second pass, he hasn't ever mentioned he wants to MPH in the stratosphere.
Suspension, converter, gearing, weight of the vehicle, boost CONTROL, driver experience and most of all, the right tune (not song) all have a major role in lowered et's.
The highest MPH and/or the fastest car doesn't always win the race.:wink: A good 60ft will lower et considerably !
Just another way of looking at this goal of Adrians.