408 paired to a TC-76?
10-18-2006, 06:31 PM
#1
408 paired to a TC-76? One shop next too me would like to build me a 408 with my hi-flo single and the other shop next too me would like to go forged 347 with my hi-flo single for daily driver street use. I would just like to get opinions on the pros and cons of each combo. They both would keep the price about the same which is 8K. That includes rebuilding the stock short and installing already purchased Hi-Flo single and tuning it with gages and installing an appropriate fuel system. I am leaning towards the 347 which will be easier to stay out of boost and get better gas mileage, however having a 408 is cool also. This will be a three day a week commuter car to work and everything else. Would the turbo 408 or 402 get much worse gas mileage than the turbo 347? Thanks for all your input! Oh would the 408 be too much motor for the good old TC-76MPS wheel?
10-18-2006, 06:36 PM
#2
I would go 347 and TC76 FTW!!!! 408 would be a little big for the turbine side. I think somebody on this board was running a TC76 with a HiFlo kit I believe. Looked like it was a direct bolt-in turbo.
10-18-2006, 06:40 PM
#4
Wow, WAAAY over 10K in an FI setup and you are worried about the price of gas 3 days a week?
I'd still take the stock inch motor with that turbo, I had the same debate as you. You may make a bit more on pump gas with the bigger one, but the backpressure is gonna stack up and you will be dead in the upper RPM region. The smaller engine should actually make more with race fuel and at high boost with that snail.
I'd still take the stock inch motor with that turbo, I had the same debate as you. You may make a bit more on pump gas with the bigger one, but the backpressure is gonna stack up and you will be dead in the upper RPM region. The smaller engine should actually make more with race fuel and at high boost with that snail.
10-18-2006, 06:51 PM
#5
I know the gas thing sounds funny, maybe I should not even have mentioned it. It was just a thought since I spend about 400 a month on fuel to go to work. I was thinking maybe an ls2 block utilizing the stock crank for an aluminum 370? That might be better than both menioned combo's?
10-18-2006, 07:00 PM
#6
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I had a 347 with my turbo kit. With M6 got 24 miles to gallon will small cam on highway. My new 402 seems to be the same I am getting it tuned this weekend. Hopefully it will make some sick power. I am expecting about 750 RWH. With the 347 I had quiet a bit of lag. With the 402 I have no lag to speak of. With the 402 I did put a set of Patriot Stage 3 heads tho. That might of made a difference too. IMO go with 402 so you can get sevral builds out of block.
10-18-2006, 09:26 PM
#7
If it's going to be the same cost for the 408 and 347 I'd say go with the 408. More cubes makes it easier to make power on pump gas which you are obviously concerned about. Who doesn't want to make the most easy power they can? Granted you might run into some turbo problems with back pressure or running out of flow, but hell you can sell your current turbo and put it towards a larger one. The only cost difference here between the 347 and smaller turbo vs that of the 408 and larger turbo is the difference between what you sell your current turbo for and the cost of the new one. Seems like an obvious choice to me, go big or go home.
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10-19-2006, 06:43 PM
#13
Originally Posted by KissMySSo1
get a bigger turbo. and use a 347. it's the way to go 
10-20-2006, 11:28 AM
#14
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Originally Posted by 52172
obviously you don't know shiznit! A tc-76 behind a 347 will put down 850 rwhp with race gas and the right combo. If I were to get a bigger turbo I would get more cubes. Right now I think I have decided 370 using an aluminum block and my factory crank. If you can't hang with the big dogs you better stay on the porch.
10-20-2006, 03:34 PM
#15
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Personally, like it was already mentioned.. if can get a 408 for the same price as that 347... got for the 408 short block. You will have a stronger setup on pump gas and not need to turn it up as much. Also... i would't worry so much about that turbo. If you ahve to sell it, then sell it. there are so many to choose from that you shouldn't allow your current turbo guide your build. Also, keep in mind, you have a hi-flo kit and make sure you can even upgrade with a larger turbo without having to modify alot or all of the kit.
good luck!!!
Go for the 408ci and a t88 t6-flanged or a t4-flanged. The t6 is the way i would go but the t4 has made some good power. (AKA parish's old single setup.)
good luck!!!
Go for the 408ci and a t88 t6-flanged or a t4-flanged. The t6 is the way i would go but the t4 has made some good power. (AKA parish's old single setup.)
10-20-2006, 03:57 PM
#16
Originally Posted by obZidian
Personally, like it was already mentioned.. if can get a 408 for the same price as that 347... got for the 408 short block. You will have a stronger setup on pump gas and not need to turn it up as much.....
That turbo will be out of breath, effeciency, and seeing tons of back pressure by 5000 RPMS on that big inch engine. Do you even realize what kind of 2.xx rear gear he will have to run with an M6 just to get through the traps?? Do you realize how hard this will be on his drivetrain? This setup will eat clutches, trannies, and everything downline from just trying to launch on such a tall gear. It's just not a good match.
10-20-2006, 05:31 PM
#17
A agree with LS2 alum block and stock LS1 crank.
I have read that many that push the envelope on a built LS1 block/LS1 crank/forged rods/pistons end up losing ring seal after 4-5K miles with forced induction making 600rwhp++++. A hone and new rings was the bandaid.
The fix was to go with an LS2 block and the ring seal problems disappeared.
I have read that many that push the envelope on a built LS1 block/LS1 crank/forged rods/pistons end up losing ring seal after 4-5K miles with forced induction making 600rwhp++++. A hone and new rings was the bandaid.
The fix was to go with an LS2 block and the ring seal problems disappeared.
10-20-2006, 05:38 PM
#18
Originally Posted by sb427f-car
I thought you had to go .030 over on a 4.00 bore with a stock crank to get 370. How are you boring an alum. block .030?
I don't know the exact CI what would it be a 368 or something like that? I just know I would like to use an ls2 block vs my ls1 block to get the slightly larger bore to help unshroud my heads.
10-20-2006, 06:02 PM
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Originally Posted by Frost
You need to look at the big picture... if the poster is NEVER going to race it on then track, then maybe....
That turbo will be out of breath, effeciency, and seeing tons of back pressure by 5000 RPMS on that big inch engine. Do you even realize what kind of 2.xx rear gear he will have to run with an M6 just to get through the traps?? Do you realize how hard this will be on his drivetrain? This setup will eat clutches, trannies, and everything downline from just trying to launch on such a tall gear. It's just not a good match.
That turbo will be out of breath, effeciency, and seeing tons of back pressure by 5000 RPMS on that big inch engine. Do you even realize what kind of 2.xx rear gear he will have to run with an M6 just to get through the traps?? Do you realize how hard this will be on his drivetrain? This setup will eat clutches, trannies, and everything downline from just trying to launch on such a tall gear. It's just not a good match.
I understand that the 76 will not be a good match for a 408, that is why i also mentioned the t88 t6/t4....
know what i mean?
Also, since you mentioned that he might never take it to the track, well, maybe he wouldn't have such a need to go out of his way and get a barrel of race fuel or properly mix his tank. Im thinking the 408 will yield a solid power growth on pump gas, therefore not having o turn up the boost where more parts are closer to their respective failure level.
Not trying to bash dude, just speaking for another perspective.
