jester1

iTrader: (1)

Does anyone here have concrete evidence on a S400 turbo. Actual hp number on a dyno being either engine or chassis. Also if no one has dyno experience how about track numbers.
I was very close on purchasing a couple of MP70's and read that a few quite a few people have had problems with them.
So now im thinking a single turbo again, not willing to spend 1200-1400 each.
The engine is a 355ci sbc
Stock bottom end b&b forged pistons 8.5:1cr
various heads to choose form
vic jr/ 750 or 850 carb
I would like something I can grow with in the furtue. Increasing cubes to 383 and 4340 bottom end 20+ psi. Right now I want to be able to put atleast 650-700 to the ground 10-15psi. In other words Ill be happy to run high to mid 9's.
Anyone here have some good sugestions.
I desperatly need to start the fab of the system so I can paint the car.

HydroStream6

iTrader: (16)

A T76 will get you where you want to be and you should be able to get one in the $1200 range. I think you can make about 900rwhp on one.

I am currently running a Masterpower T70 and havent had any issues with about 6k miles on it. I probably will upgrade to a Precision T76 though just because the T70 will only make about 700rwhp.

Snyper

iTrader: (27)

Or you can call JOSE from FI and get one of the turbonetics TC-76 turbos with a 1 year no questions asked warantee for around 1000$

jester1

iTrader: (1)

thanks
pardon my ignorance what brand is the tc76?
Im not sure why but ive read different graphs and track times with people using a 76mm and its seems that some are at 650 rwhp and others are at 850rwhp the ones in questions have extreamly "similar" combonations and running at approx the same psi, so my question is what can cause the difference?

BlackCamaroSS02

iTrader: (8)

Think the brand is turbonetics jester1

Snyper

iTrader: (27)

yeah turbonetics, well known brand. And it comes with a polished compressor cover standard as well.

engineermike

I've wondered about this myself and I think the big difference is auto versus manual. My 695 rwhp auto runs the same mph as other people's 850 rwhp stick cars. There was one guy that made 990 rwhp and his was only about 5 mph faster than mine, even though he had almost 300 rwhp more!

jester1

iTrader: (1)

EngMike. your system is maxed out correct on the engine dyno @approx 900hp.
Your at 695 rwph diff of 150hp. So if you loose 150 through the auto how can the two run the sam mph? Now im really confused? The 990rwhp is a diff of 300rwhp with only 5mph gain. Correct me if im wrong but the 990 rwhp should be in the low 8's. On the mustang board one fellow has a331ci afr185 heads aod/od and 840rwhp @23psi and 9.30et. should that not be in the 8.80 range if not faster?
those colorfull bottles are starting to seem real nice again.

I went to scroll the FI site you recommended "Jose" the airerks s80, is that not the modded s400 with the 80 wheel?
Would the gt42-76 be the same as the t76s?
thanks

engineermike

jester, are you worried about dyno numbers or track mph? After I pulled 146 mph at the track, I went straight to the dyno, excited to see what power it was making. I was dissappointed when it only put down 695 rwhp. That's when Madman pointed out how ridiculous I was being. "Let me get this straight. . . the car ran great at the track, but you're upset because it didn't dyno higher?" You see, the guys who build truly fast cars really could care less about chassis dyno numbers. Auto transmissions, especially those with lose converters, drastically affect the dyno readout.

JustAnIlluzion

iTrader: (60)

I have not heard anything bad about MP turbos over the years on various forums

LS2Camaro

iTrader: (5)

Do a search on this forum, and it will tell you otherwise. Just ask the Doctor of turbo's.(DrTurbo). In the end the decision is up to you, but do you want to chance messing up your engine? Not me
This is quoted from DrTurbo in the link below
https://ls1tech.com/forums/showthrea...er+Power+Turbo
http://www.turbomustangs.com/smf/ind...?topic=69566.0

jester1

iTrader: (1)

Mike you are correct doesnt really matter what you make but what your car can run with what you have. However dosent what you put down drastically affect what you run. I just dont want to end up buying the wrong turbo.
The post LS2 has quoted was what I read a few days ago which was the last straw as they say. When a dealer stops carring a product due to it being bad especially due to warrent issues then it must mean something. Now Im north of the boarder and that would equate to double the time unfortunatly.

Im actually really suprised that no sponsers have put their two cents in yet. No one wants to make a sale?

engineermike

They type of drivetrain drastically affects the rwhp numbers. However, it doesn't seem to affect the mph the car pulls. What exactly are you trying to figure out? If a 76 is a good replacement for a 70? There isn't something funny about a 76 that makes it inconsistent. In fact, I dare say that ANY 76 will outperform the MPT70.

jester1

iTrader: (1)

When I started looking for a turbo it was a 76s, now Im woundering if its the right one for me? I dont want to repurchase another one in the near furture. thats why I was about to concider purchasing two MP70's and deal with the lag for now. Either way in the long run what I want to see is the score board light up with 8:99 then ill be happy. I know the base engine wont bring me there but when upgraded to good reliable components I want it too.

engineermike

Allright, now we have something to work with.

You can get a 8.99 out of a 76, but it will have to be the GTS .96 Tang at a minimum. Even then, it will be tough. You will be pushing the 76GTS to its very limits and it will require some weight reduction. With those goals, it would be much easier to get there using a large frame PT88 or 91, or a pair of 63's or 67's.

jester1

iTrader: (1)

ahhh. now where are really getting somewhere . As you can see now where the delema started from. The cost of two was the cost of one. So if Mp sucks then Id have to go to say majestic @ about 900-1000 each. Which now makes the 1200 for a 76 a decent buy. Which started me asking question once again would it be enough, when i started researching it seem it was enough for some but not other, kept digging to find like i mentioned before the combos word very similar but different outcomes. Thats when I tried to enquire about the s400 which says its good to about 1000 @ half the price of the 76. But seems no one yet has run one at the strip or dyno.
All in All in want my cake and i want to eat it too. Is that too much to ask?
Is the gt42 comparable or better than a 76?

engineermike

I don't think you can reach the 8's with a turbo that max's out at 1000 hp. The 76GTS will go to 1100 - 1150 and even that would be difficult.

I did some searching around on the turbomustangs.com site because the 76 mm turbo's are very popular over there. I found results like this:

"I went 9.39 at 146 with a on center q trim T76. We had a little left in it but not much. Switching to the R trim Innovative 76 allowed us to pick up a couple of tenths and 6mph."

"1 run 363 with a ptk 76 mm kit 9.6 @145 up graded to a bigger intercooler no issues 15 npsi"

"76GTS turbo. Best time so far 6.06 @ 117"

"331/PT-76GTSH 5.98@122, 1.49 60' 3450#s"

Seems like there are alot of 76's in the mid/low 9's at around 150 mph. As I said, it's possible to get in the 8's, but it will be difficult. If the s400 has a lower power limit, then don't count on it getting you in the 8's.

As for the GT42, you can get a GT42-76. At first, it was supposed to support more power than the GTS since the exhaust side was physically larger and you could get larger A/R's. However, I think someone determined that it wasn't really any better (but that part's fuzzy).

I think your best bet is to get a PT88 and make sure you use a 3.5" or 4" downpipe.

Mike

jester1

iTrader: (1)

Mike thanks for the quick replies they are very appriciated!
The 331 ci combo is "Pauls" stang right? if it is thats the one that got the hamster turning once again! So its back to the 76 vs 88 which is where I was at last year when I started debating to go turbo once again. the 76 should have better street mannars vs the 88 in a 355. You use it in your 388 did you have any pressure issues or is that a selling point for dealers? I was on the FI site under the airwerks tab I saw the s series from s74 to s80 Do you know what they are based off, any idea it ists the same as "Dave's" moded s400/80?
May be I should slap in a jt9 or similar I think that will work.
Since Im not next door here is a drink on me
three americans = one Canadian light

engineermike

Ah, yes, one of my favorite subjects. . .

First of all, you can get the backpressure pretty low with a 76GTS even at 350+ cid. I built a combo earlier this year using 377 cid and a T76GTS. At 18 psi boost, it only had 26 psi backpressure. The key is to have a very good exhaust downstream of the turbo (ours was a short 3.5" downpipe and nothing else) and also a free flowing cold-side (the less pressure drop through the filter, intercooler, and TB, the more boost makes it into the plenum, making the backpressure ratio better).

Secondly, I don't think it's the backpressure that hurts power with alot of cid. Well. . . it does, but it's not created the way most people think. It's not that the 76GTS causes more backpressure on large cid. After all, hp is airflow, not cid. If you make 1000 hp with 180 cid, then it's going to take 40 psi boost to get there. However, if you make 1000 hp with 350 cid, then it's only going to take 20 psi to get there. If the 76GTS is compressing 1000 hp worth of air, then it's going to create 50 psi of backpressure. So, the 180 cid Supra engine has a backpressure ratio of 50/40, or 1.25, whereas the LS1 has a backpressure ratio of 50/20, or 2.5. It's not that the LS1 has any more backpressure, it's just that the compressor doesn't build as much boost since the engine has a greater capacity/air comsuption rate. Clear as mud?

Now, which one will make more power? That would be the 180 cid. But wait a second, I though that it had the same air flow rate and backpressure as the 350 engine? Think about this, though: the 350 cid engine has alot more piston area and stroke that the 50 psi works against. I ran some rough calc's and, if a 400 cid engine has to work against 50 psi exhaust pressure, it will lose 150 hp. A 350 cid engine will only lose 120 hp against the same 50 psi. Meanwhile, a 180 cid engine, even at 1000 rpm higher, will only lose 76 hp. So, a 180 cid engine will wind up making about 75 hp more than a 400 cid engine at the same air flow rate.

Mike

Slowhawk

iTrader: (12)

So far I've found Turbo's are the same as superchargers. We just oversize the Turbo alittle for your goal to keep the turbo in the efficiency range.With the right converter lag won't be a problem.
If you want to go 8's I'd run a T88 or S-85,S-88. A 76mm will be pumping to get you there and might fall short.
Of course depending on the CI and what the motor is built for a 91mm might be better.