Turbo's for the street
 

Are 100mm turbos to big for the street,I'm kicking around a TT 499 sbc

twin 100mm turbos? :eek: what HP are you looking for, 4000 or so? :wow:

Jody

not to hijack... but the question has been haunting me... what size turbos to mount on an ls1, and i dont want 1400Hp, but somthing realistic... 650 rwHp?? or that teritory.. we have 95 octane available here, and the engine is an ls1, 8:1 comp, good heads.. dart? and a good intake.. air/air intercooler..

is it worth going ball bearing, they are more expensive and do not come with a warranty...

Well that's the reason I asked,I'm a nitrous guy so this whole turbo deal is a new world to me.

I would like to be in the 1300ish bracket.

THE 100MM'S TURBO'S OVERKILL , A PAIR OF 70'S WOULD BE MORE THAN ENOUGH. AND A NEARLY 500" SB WOULD BE A TIME BOMB. THE CYL. WALLS WOULD BE QUITE THIN , AND THE STROKE REQUIRED WOULD MAKE FOR A WEAK CRANKSHAFT. NOT TO MENTION THE PIN LOCATION WOULD COMPROMISE THE RINGSTACK MAKING THE PISTONS NOT VERY DURABLE. I THINK THE SAFE LIMIT FOR MOST TURBO SMALL BLOCKS IS A 427CI. IT'S A 4"STROKE WITH A 4.125 BORE THIS LEAVES THE BORE STABLE,AND LEAVES ROOM FOR A COUPLE OVERBORES IF YOU HURT IT. BUT IT STILL NEEDS A TALL BECK BLOCK FOR BEST RESULTS. IF YOU WANTED TO STAY WITH A SHORT DECK I'D GO WITH A 3.750 STROKE. CHECK OUT NELSON RACING ENGINES AND YOU'LL SEE WHAT A MOTOR LIKE THIS IS CAPABLE OF.

I didn't mean to be a smart aleck, but a 100mm turbo is HUGE, supporting about 2000 HP depending on model. That's for ONE turbo; two is insane for anything on the street and the spool time could be measured in minutes. Kidding on the spool time, but you get the idea.

What is your HP goal? As far as small blocks and turbos, most of the real high powered setups are under 400 inches.

Jody

I just finished acouple 499 dirt late model engine's,tall donovan blocks.both made 1100hp and a friend of has a pro street vette with a 648 and want's to change to TT's and use a 499 for base.

I noticed most go smaller cube's,me and freind of thought it would be cool to play with a bigger inch motor and TT's has in my other post it's replacing BBC.

But I was looking at what alot of the 10.5 racer run for turbo's and just kinda through a # out to see what response I got.

In my experience there are trade-offs in forced induction builds depending on cubic inches. My 468 made a bit more HP than my 540 with the Procharger at the same boost. The 540 beat it in torque though. Seems like there is so much weight in a big inch stroker that maybe the smaller setups are more ideal, at least as far as HP is concerned.

It just seems all the fastest small block turbo guys seem to be in the 370-380 cid range. And they don't have a cubic inch limit, or budget concerns. Seems if a 450-500 inch small block would make more power and a lower et they'd use it.

Jody

Don't forget that dental-floss thin headgaskets between the bores on big bore SB's can cause you quite a few headaches when you throw a lot of boost at it.

Go big enough on the bores to unshroud the valves, but not so big the sealing ability of the headgasket is compromised. On a SBC with standard bore spacing I don't think I'd go over a 4.125" bore... but that's just my opinion.

As was already mentioned, going too big on the stroke poses other problems like piston speed and a compromised ring pack.

I also agree that somewhere in the 370-390ci range is the "sweet spot." I'm planning on building a 388 using a 4.125" bore Dart block with a 3.625 stroke crank sooner or later, unless I decide to make the jump to LSX.