I asked this in another thread but I need clarity:

If a motor has 450 RWHP N/A and than you add 15psi of boost by way of a turbo, the motor should now have approximately 900 RWHP, right?

Now lets say you add another 15psi...30psi of boost. Does the 900 RWHP now double to 1800 RWHP or do you roughly add another 450 RWHP to the 900?

1350 RWHP


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1350 Theoretically

 

None of the above

 

it's actually 14.7psi, but inaccuracies aside, yes, you "theoretically" would double your horsepower, but you would have to be able to keep all other parameters the same.

 

Just wondering because Gayle Banks puts 35psi to their 427 TT DART engine, making 1,600 FWHP. I was just trying to figure out what the engine had N/A. I spoke to their builder last week on the phone and they use 9:1 cr pistons, so I guess its a pretty good N/A engine too, maybe 500 RWHP. The heads flow 440 cfm.

 

yea 14.7 I wasnt paying attention

 

To many variables. Turbos used, cubic inches, cam specs, piping diameter (hot and cold side). In a perfect world though yes it would be close.

Jose

 

Some say too many cubes is bad for turbo applications. Some say the stroke should be smaller than the bore.
What's your take on that?

But LPE has their 427 TT and Gayle Banks has their 427 TT. They're supposedly the turbo guru's of the country.

 

To many cubes is bad to a certain degree for most turbo setups. If the turbos are not picked properly then backpressure is high, EGT's are high, and you will have problems. Reason banks and LPE do big cubes is since their packages are designed for daily drivers that want zero compromise they use undersized, but quick spooling units and big cubes means you can still make good numbers on pump gas. Also the level of hp they make for the street is not much. Compare their systems to some of the guys on this board that run smaller cubes but more efficiently picked head units and you will see the difference. But to have great efficiency typically does cost you some lag.

As for the stroke vs bore......don't put much stock in that. We have customers running 2JZ's with an 87mm bore and 94mm stroke (3.4 stroker) making 1400+ crank hp.

 

BTW, their are only a few folks on the planet I would consider turbo guru's. And by guru's I mean they understand the science and physics of turbos and how to match, size properly and weigh all the variables of a setup mathmatically and by experience. One is Corky Bell, the other was the late John Meyer.

 

I spoke with the guy who builds the engines for Banks this week, he made 800 fwhp with a 366ci engine and pump gas, turned up the boost a bit, added an IC and 104 octane, and the same engine made 1,200. He said the engine had more in it too. He said his 427 will make 1,600 fwhp easily and be reliable.

He's talking DART block and heads. He also said he's built LSx based engines and they can be built to handle hp in these ranges. But the DART stuff is better and stronger.

I guess they know how to match everything than.


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That's one too many "he said's" in an arena that requires the best precision and accuracy to keep things working perfectly. I wouldn't go by what "he said"; many people can claim anything....real-world results are the key element here.

I think you're just trying to reassure yourself for peice of mind that they know how to do everything. Me personally, I'd trust Jose before most others. The key is to talk to a few people that know what they are doing to give yourself a general direction, and from there you can weed out who is doing what correctly, and who is doing something wrong.

 

in perfect conditions, like everyone else here said, yes.... some other things to consider when throwing around numbers in your head, when you pick the NA HP number, imagine that setup with the timing and fuel that it would run at that boost level with the fuel type also, and subtract how much of a power loss that would be on the NA motor first. so your 450 rwhp car becomes a 400 rwhp car if running on pump gas, etc. then 15 psi, would be a 800 rwhp car. this is assuming efficient boost, 10 over ambient or less intake temps, etc.

 

i would go with your statement if you applied it to flywheel, not rearwheel.