i think your gonna need to do some minor engine compartment modification to get that to fit. At least the turbos will get proper cooling cuz they will be hangin out of the quarter panels.

 

yeh i dont know what happened. they should fix it.

 

Jim,

I will have my twin ball bearing T67 GT 40 hybrids up and running soon, I am hoping the spool time won't be a problem at all. On paper the turbos will be good for over 1600 Flywheel. I was in the same boat as you trying to figure a way to get these heavy *** trucks to spool quickly, but think the 67's will be pretty responsive. I guess we will see soon enough.

I like the way you are thinking though, and feel there is room for improvement on system design.

 

y not try something like they do on diesels. i think diesel inovations did something were they had a small turbo that fed a bigger turbo so it spulls fast then the larger turbo feeds the high end. it may have been mentioned already though.

 

Well, you really only run sequential inline turbos like that when you want to make huge boost numbers (like diesels do). No real reason to do it on gas motors since they can't take all that dynamic compression.

 

parish8,

While I like your idea and all do you have your heart set on sequentials just to be different or is the spool up/lag the main reasoning for going that route? I have to tell ya that there are WAY less complicated ways to get rid of most if not all turbo lag when using the bigger spinny thingys.

1. Fatten up your A/F ratio for spool up. Turbo's not only use exh velocity they also use the heat (expanding gasses) to spool up. Fatten the A/F for spool up to let the unburned fuel into the turbine side to light off and help with spool. Its REALLY easey to do with aftermarket DFI where you can use a switched input to bring on a "spool up tune" or the like.

2. Retard the timing...Same thing as above but using timing instead of fueling to get extra fuel/heat into the exh.

3. Small shot of N2O right before launch. Same principal as above as it dumps a LOT of heat into the turbine....instant spool up. The down side is that if youre not on top of the tune or the N20 set up things can get ugly fast. Bascially this isnt a "throw the parts under the hood and mat the gas" set up.

4. Two step rev limiter. This will work fine on an automatic turbo vehicle and a couple of the serious (low 9s) syclone guys use them for spool up at the line for spooling 88, or bigger, with just a 265cid V6. It fattens the A/F ratio just like numbers 1-3 as well just by interupting the spark randomly as Im sure youre aware of. This method is prolly the easiest and most user friendly but all of that popping and banging can be hard on a vehicle that has more of an exhaust than just ~4" open collectors like a pure race car does. Basically if there is a weak weld or component in the exh system you'll become aware of its location very soon LOL.

If you must have sequentials for the "WOW" factor as well as spool up then ignore everything I just said

 

i do spray it off the line when i am racing. i can also brake boost it without any nitrous if i have 20sec's or so to wait. i am sure tuning would help a little especialy with my drag racing lag but i am looking for the day to day spool up to be faster. rolling along at 30mph and punch it from a near idle.

this post was more of a question of would it work. would it spool faster and still have the same top end as before, not so much a question of would it be worth the extra work. somewhere someone posted up a factory drawing that was prety much exactly like what i posted up so i guess it isn't a new idea.

 

I gotcha...I was thinking you were having spool up issues while racing. Getting drivability spool up to the best it can be is all about tuning which is time consuming to say the least as Im sure youre aware.

FWIW, the new GTQ ball bearing stuff from garrett is helping with spool up from what we've seen on small CID motors so they may be worth looking into. A good friend of mine sells them and he'd be more than happy to help with info and application if youre interested.

His site is www.turbotime.us if youve got some time to kill.

 

Jim, what if you eliminated the complexity in the exhaust track?

What if you did something like a GT37 and a GT72 and just used the one way flapper on the 72? Let both turbos spool normally, but restrict the 37 to 10 psi or something and get the big boost from the 72? I know there's got to be a problem with this idea, I just can't see it this am lol

 

Have you looked into any of the variable geometry turbos offered by Garrett? Everytime I go to their site, there's nothing but hype about it, but they don't have any comp. maps or hard info. I'm willing to bet a big variable geometry turbo would spool hella fast. I know they're used on the new deisels, but they would kick *** in a twin gas situation.