Topic: looking to add some cheap horsepower ;-)..

[77perudo]

nice.. i think im really leaning toward those.. again im sure a but of performance gain over log manifolds, and alot easier to work with. thx for your input.

[cmk-2]

If you want true real world gains and with dyno runs to back them up look at my new thread 1978 W72 dyno numbers. Base/stock was 177 HP and 239 TQ with the ram air manifolds 2 1/2 duel exhaust and a Cliff Ruggles HP carb rebuilt kit went to 240 HP and 287 TQ. BW the TQ peak was moved up from 2,800 RPM to 4,000, That's getting it done....

[77perudo]

  nice.. will check out that thread thx..

[Angelo]

77peduro, where are you located?

I also run ram air manifolds with the he oversized 2.45 outlets. Because of this restriction though there is no need to have the rest of the exhaust larger than 2.5". Are you wanting to replace the entire exhaust system or just the manifolds and use existing pipes?

[77perudo]

im in NJ.. haven't had it on a lift yet to look at the entire exhaust. for the power range this car will be in the 2 1/2 size would be fine. goal is around 400 HP all said.. will do things in stages tho. probably focus on heads / exhaust first.. then try to find out what is in the engine as far as cam goes.. its new when engine was rebuilt from previous owner.. swap out with something if necessary.. then intake / carb last.

[72blackbird]

It takes a bit of work to reach 400 hp in a 400- a cam swap, some RARE manifolds and a new exhaust alone won't do it. It also takes improved cylinder head flow, increased static compression, improved carb and ignition upgrades and tuning. First off, are you working with a W72 or an L78? Secondly, what are you planning to do in the rebuild? Stock 400's benefit greatly from swapping over to ported heads with small chambers, big valves and screw-in studs in addition to a larger duration cam with high lift.

Geno

[77perudo]

totally agree its gonna be a bit of work.. high compression heads with large valves and screw in studs etc., RARE exhaust manifolds, along with the rest of exhaust system. possibly better intake and carb if tuning does not give me the results im looking for. but want to plan this in stages as to not break the bank with each thing i want to do.. might focus on RARE manifolds and exhaust first.. then move onto the heads. then recoop some funds ;-).. see where it goes from there.. maybe intake and carb after those things. maybe a better ignition system. L78. 6X - 8 is the stock heads.. i plan to swap those for an earlier vintage set. was also thinking down the road again if still dont have what im looking for performance wist might look into the ohio crank rotating assembly to drop in there.. add CI.. i also know if i go that rount i wuld need the larger chamber heads so compression is not way over the top..

[72blackbird]

perudo,
Forget about using the L78 block with a stroker kit- it is too thin in the main saddle area and will crack at the dowel pins. PMD tried to put a band-aid on it and used rolled sheetmetal main cap dowel pins, but many still cracked- a stroker kit will definitely make the block fail. Get a 481988 400 block and use that for a stroker kit- build it right from the ground up and it will reward you with excellent power.

The plus of having an L78 is that you can use the 6x-8 heads on your stroked 400- they usually have 98-102cc chambers, which will give you a pump gas friendly 8.9-9.2:1 SCR. No problem with 91 octane there.

Geno

[77perudo]

had the carb tuned a bit.. but there are issues with it.. secondarys are not opening properly.. probably need a rebuild. i just ordered an edelbrock performer intake, and a edelbrock 750 carb. and probably keep the qjet and intake in storage because its original to the car. i am most likely going to put higher compression heads like the 16's or something similar 72 cc chamber, large valves etc. my question is if i do the ram air manifold/header and swap heads at the same time as the manifolds is it easier to do both at the same time?? i saw some install vids for the ram air manifolds and said to lift engine a little bit etc.. would i still have to do that if swapping heads also.. if heads are out i would have more room to work with the manifolds and dont think necessary to lift engine at all.

[77perudo]

perudo,
Forget about using the L78 block with a stroker kit- it is too thin in the main saddle area and will crack at the dowel pins. PMD tried to put a band-aid on it and used rolled sheetmetal main cap dowel pins, but many still cracked- a stroker kit will definitely make the block fail. Get a 481988 400 block and use that for a stroker kit- build it right from the ground up and it will reward you with excellent power.

The plus of having an L78 is that you can use the 6x-8 heads on your stroked 400- they usually have 98-102cc chambers, which will give you a pump gas friendly 8.9-9.2:1 SCR. No problem with 91 octane there.

Geno

thx geno for the info... i have to look at my block and im aware that alot of them are weaker.. but was under the impression the if its "XX" labeled block is just as good as the earlier vintage block for strength etc..

[Angelo]

You should not have to lift the engine at all. Headers require lifting the engine, Ra manifolds can be rotated, etc to get them in. If the heads are off the engine that would be the time to put the manifolds loosely into position.

[77perudo]

thought so.. thx... might plan that in the fall..

[Angelo]

I am very pleased with my RA .manifolds from ram air restorations. I did use "Pypes" brand down pipes though. If I did it over again I would get the downpipes from RamAir Restorations as well. Just remember they sell the flanges separately.