BHP estimates please

dbv8 · Post by **dbv8** » Thu May 17, 2012 12:37 pm

My mates nearly finished putting together his latest engine set up and i was wondering what bhp he should be expecting.

Its a 440 Mopar with a mild roller cam, roller rockers, CR is down to 9:1 and hes slapped a slightly underdriven 8/71 blower with 2 x 750 (IIRC) carbs on top.

kiwicar · Post by **kiwicar** » Thu May 17, 2012 1:32 pm

Hi
He would pick a mopar! the only big block that has heads that range from terrible to not all that bad from the factory. I think they rated factory output from about 175 bhp to 390 odd depending on cam and heads with most ratings between 225 and 335 so really you need to find out what the original output of the engine those heads came from. If it is under driven by about 20% and the heads came off an engine rated at 335 bhp, you would probably see about 550 to 650 bhp, if they were off a 175 bhp engine and the same underdrive you would probably see 350-375 shortly before it all went bang.
This engine does not like to rev so it is all about head flow to get it to make power.
Best regards
Mike

gasserman · Post by **gasserman** » Sun May 20, 2012 8:12 am

if hes using 440 heads he will make good power ,these engines will rev to 6000 rpm or higher with steel h beam rods ,the blower will compensate for the head flow ,estimate 650hp with plenty of usable torque ,definate tyre fryer

bigaldart · Post by **bigaldart** » Mon May 21, 2012 1:17 pm

With a good crank and rods, stock 440 or hemi rods then a 440 will rev to 7200 safely, course most factory heads won't get anywhere near that. But the bottom is not as fragile as some people think.

Alan

kiwicar · Post by **kiwicar** » Mon May 21, 2012 1:26 pm

Hi
OK I stand corrected, just every article I have read on this engine (and I have read quite a few as I was thinking of building one once) recons it won't rev beyond about 5500 on standard crank and rods without going bang. Quite a bit more on a forged lightweight crank using BBC rods and journal sizes but they said the standard items were to big and heavy and tended to crack the block if reved.
Bestr egards
Mike

gasserman · Post by **gasserman** » Mon May 21, 2012 2:23 pm

early forged crank 6pack rods 7000rpm
my old 505ci engine forged crank alirods iron 906 heads 750 roller cam 8500rpm

kiwicar · Post by **kiwicar** » Mon May 21, 2012 3:04 pm

Ah,
Slight difference in spec to a cast crank there!

Best regards
Mike

dbv8 · Post by **dbv8** » Wed May 23, 2012 10:57 am

I forgot i started this

Tonys back home now and finishing off the install of the blower.

To add.... previously it put 300bhp @ wheels on John Sleaths rollers at modest rpm but had more to give.
The Interceptor is in full street trim and has run 12.5 over the 1/4 on the NA set up. A pair of small MT street radials, a trick box and a moderate stall converter all help a little too.

Hes hoping for 600+, I think he may get more. A fully street trimmed Jensen will soon be running mid 11's I think. Then hes got the gas to play with. It had 400 @ the wheels on a 125 shot.

kiwicar · Post by **kiwicar** » Thu May 24, 2012 9:30 am

Hi
If it is a 300+ at the wheels engine and he sticks an 8-71 on it I think he will not be disapointed with the output!
Pity he didn't have the crank off set ground to take BBC rods, the extra capacity would have worked well with a big blower like the 8-71.
Best regards
Mike

dbv8 · Post by **dbv8** » Thu May 24, 2012 3:09 pm

Whats his face going to be like when its running

ChrisJC · Post by **ChrisJC** » Thu May 24, 2012 3:37 pm

What is it?, a Jensen?

Chris.

dbv8 · Post by **dbv8** » Thu May 24, 2012 3:53 pm

ChrisJC wrote:What is it?, a Jensen?

Chris.

Yup. The owners club will be up in arms

kev_the_mole · Post by **kev_the_mole** » Thu May 24, 2012 4:58 pm

The owners club will snub him to death! We could be twins

You can calculate the worth of a man by the number of his enemies, and the importance of a work of (automotive) art by the harm that is spoken of it.

Gustave Flaubert, Letter to Madame Louise Colet (June 14 1853).

kiwicar · Post by **kiwicar** » Thu May 24, 2012 5:10 pm

he looks a happy man
shame in some ways he didn't do it to an FF, they owners club wold be out in force. . . . .
Very nice I am jealous
Best regards
mike

bigaldart · Post by **bigaldart** » Mon May 28, 2012 1:00 pm

that is a 8V-71 so puts out about the same as a regular 6-71. Rotors are smaller diameter on the V series as they also had a turbo! It will displace about 410 cu in per rev, so about 10-12 lbs of boost at 1-1

Alan