Hi Guys,
I know theres been loads of discussion on how much boost you can put into a standard rv8 engine before it melts, searching the forum it seem to be around 8-10psi on a standard engine. What I wanted to know is what 8-10psi relates to in HP terms, anyone got any ideas??
I've got a 3.5 in bits at the moment, (still), just giving it a clean and polish before rebuilding it and would like to boost it, nothing silly as i'd like to keep the engine standard to keep costs down to a minimum.
Thanks guys
RV8 Twin Turbo
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this is very ball park aproach but to start with:-
Take a guess at the figure for the output for the spec of the engine if you don't have the trubos (but assuming you have a sensable Compression ratio).
say 3.5 rover with lightly ported heads, injection 215 at .05" cam decent exhaust manifolds about 205 bhp
then take this figure and the boost figure you hope to use (say 10 psi)
add 14.7 to your boost figure (24.7)
multiply your BHP figure by this
so 205 X 24.7 = 5063.5
divide this by 14.7
5063.5/14.7= 344.5
multiply this by the efficiency of the turbo (about 75%)
344.5 X 75/100 = 258
right if you have a pretty good intercooler/charge cooler add about 15% to this
258x 1.15 = 297 BHP
if you use really bad exhaust manifolds you can probably take another 5 to 10% off this. If you prep the heads for a turbo and make the most of the exhaust side and get a really good turbo cam you may get another 4 to 5% for each.
It is all a bit approximate but will get you in the range.
Best of luck
Mike
Take a guess at the figure for the output for the spec of the engine if you don't have the trubos (but assuming you have a sensable Compression ratio).
say 3.5 rover with lightly ported heads, injection 215 at .05" cam decent exhaust manifolds about 205 bhp
then take this figure and the boost figure you hope to use (say 10 psi)
add 14.7 to your boost figure (24.7)
multiply your BHP figure by this
so 205 X 24.7 = 5063.5
divide this by 14.7
5063.5/14.7= 344.5
multiply this by the efficiency of the turbo (about 75%)
344.5 X 75/100 = 258
right if you have a pretty good intercooler/charge cooler add about 15% to this
258x 1.15 = 297 BHP
if you use really bad exhaust manifolds you can probably take another 5 to 10% off this. If you prep the heads for a turbo and make the most of the exhaust side and get a really good turbo cam you may get another 4 to 5% for each.
It is all a bit approximate but will get you in the range.
Best of luck
Mike
poppet valves rule!
As with all engines it is best to start with the most suitable one for what you want, if you want a 200 bhp and reasonably large amount of torque then (especially if you already have one) it is cheep, if you want 220 BHP and have a 3.9 to base it on then that is also fairley cheep. If you need to rebuild it of want major than these figures then it get very expensive very quickly (unless you have alot of experience and skill at blueprinting and can flow your own heads.
Depends what you want really, SBC takes an aufull lot of beating for power per pound (especially if you are prepared to wait for the right bits to come along second hand) but it is heavy.
302 ford, lots of cheep easy power to a point but lighter and a bit more compact than the chevy.
LS series chevy lumps are really becomming the bargin power house, especially if you look at the truck varients and the 5.3 and 4.8 engines, a 5.3 does everything you can do with the 5.7 and will produce virtually the same power as the 5.7 when tuned, but they start about $1000 less on e-bay.
then there is the caddilac northstat and the audi V8s....
Mike
Depends what you want really, SBC takes an aufull lot of beating for power per pound (especially if you are prepared to wait for the right bits to come along second hand) but it is heavy.
302 ford, lots of cheep easy power to a point but lighter and a bit more compact than the chevy.
LS series chevy lumps are really becomming the bargin power house, especially if you look at the truck varients and the 5.3 and 4.8 engines, a 5.3 does everything you can do with the 5.7 and will produce virtually the same power as the 5.7 when tuned, but they start about $1000 less on e-bay.
then there is the caddilac northstat and the audi V8s....
Mike
poppet valves rule!
hello,
yes quite a bit of experiance of buying from the states, (various posts on here) all pretty good. You need to be sure of what you want as practically sending it back if it is wrong is right out
so do your research first.
you will be charged duty and VAT on everything including the postage, duty seems to be 0 to 5% depending on I am not sure what! Vat is always 17.5%
Get a quote in delivery first, and confirm it when you come to pay, try and use a credit card with good insurance on it (ie a gold card or better if you have one) to pay for whatever you buy then you have somthing to come back on if you do get problems. If you buy off ebay and use paypal you will probably have to go through the account validation process, before you bid as it takes a couple of days to sort out. I would look for items from the uk ebay but on the international vendors feature as it is a pain to spot the perfect bargin only to find the guy does not ship outside the 1st 48.
try and get them to send large items surface delivery, it will take a while but save you £100's of pounds. and get them to use us mail if you can as it comes in parcel force and they are dead easy to use (the parcelforce vans are "bonded" and they are customs agents which means they clear customs on your drive when they deliver.
The guy with the V10 in a seven chassis on here bought his engine and gearbox from the US might be worth a PM to him.
good luck
Mike
yes quite a bit of experiance of buying from the states, (various posts on here) all pretty good. You need to be sure of what you want as practically sending it back if it is wrong is right out
so do your research first.you will be charged duty and VAT on everything including the postage, duty seems to be 0 to 5% depending on I am not sure what! Vat is always 17.5%
Get a quote in delivery first, and confirm it when you come to pay, try and use a credit card with good insurance on it (ie a gold card or better if you have one) to pay for whatever you buy then you have somthing to come back on if you do get problems. If you buy off ebay and use paypal you will probably have to go through the account validation process, before you bid as it takes a couple of days to sort out. I would look for items from the uk ebay but on the international vendors feature as it is a pain to spot the perfect bargin only to find the guy does not ship outside the 1st 48.
try and get them to send large items surface delivery, it will take a while but save you £100's of pounds. and get them to use us mail if you can as it comes in parcel force and they are dead easy to use (the parcelforce vans are "bonded" and they are customs agents which means they clear customs on your drive when they deliver.
The guy with the V10 in a seven chassis on here bought his engine and gearbox from the US might be worth a PM to him.
good luck
Mike
poppet valves rule!
