More power from a 3.9 without changing cam

So want to know what I can do to get more power out of the 3.9 efi without having to change the cam or anything else expensive.

I thought about better spark plugs and air filter perhaps but what else?

Cheers.

Both of those items may make your engine run better but it won't increase power. For more power u need to get more fuel in and then the exhaust gasses out.
Fit a sports exhaust system and u may get one or two BHP extra.

discool said:

Both of those items may make your engine run better but it won't increase power. For more power u need to get more fuel in and then the exhaust gasses out.
Fit a sports exhaust system and u may get one or two BHP extra.

Click to expand...

it would be a bit more than that - but it already has a straight through system. Would like to decay it but unsure what to do given the Lambda sensors.

more fuel + more air = more power which will be helped by a K&N and a better/larger air intake. It is claimed that a K&N or similar with a sufficient size intake would add about 3hp to a traditional V8 engine.

I know about a fair few things that could be done to the engine but not sure which would be my best bet. I have seen a 3.9 RRC dyno 300hp before but that of course was a complete rebuild with high lift cam and custom ECU

I was told by someone who is into muscle cars and racing them that a better spark plug (bigger spark) will help improve things a little.

hi

dont wanna **** on your party but whoever told you that talking crap..

only way to make more power is to pend ££..end of.

so assuming you gotta a 100k + miles 3.9 then its running 100hp (ish)tops..due to cam being worn..

plugs will not add power..k and n will also add none..as if you would notice 3hp anyaway??.cold air intake might add aee bit..and its free..

but if i was you i would do a cam and lifter change..atleast then it will be back to stock hp..(and a full service, which by the way will cost the same as a cam)

to get power you need this..



but this does cost..but it works, unlike spark plugs etc..

zen said:

hi

dont wanna **** on your party but whoever told you that talking crap..

only way to make more power is to pend ££..end of.

so assuming you gotta a 100k + miles 3.9 then its running 100hp (ish)tops..due to cam being worn..

plugs will not add power..k and n will also add none..as if you would notice 3hp anyaway??.cold air intake might add aee bit..and its free..

but if i was you i would do a cam and lifter change..atleast then it will be back to stock hp..(and a full service, which by the way will cost the same as a cam)

to get power you need this..



but this does cost..but it works, unlike spark plugs etc..

Click to expand...

Ok thanks for clearing that. I don't know the milage of the engine but it certainly seems to go well. Deffo more than 100 hp

you would be surprised how much power you lose with old cam..

but really..a new cam and followers cost £100 ish..as does a set of plugs, leads, dizzy cover and rotor arm..so £200 to get it running good..thats not bad..

I agree with Zen about the cam being about the most important item at this sort of mileage. My last 3.5efi had done around 140k but had a top end overhaul (standard parts) at 120k. Impressed by the compressions (average 165) I put it on a rolling road & got a read-out of 170 brake. Tuning on a budget (plugs, leads, filters etc.) may make the engine run better, but real tuning requires engineering.

Ok cheers

Zen is right. Cam wear will kill the power and is likely over 100k without good oil frequently changed. Besides that its like you say more air and fuel in and improved flow out. Bore out and fit larger throttle k\n tubular manifolds. Straight thru exhaust will make a big noise and fool you into thinking its faster, but the restriction is the stock manifolds.

Ignition timing can often be a bit late and immediate gains can be had getting it right.
Imo the stock ignition is adequate. Recently changed from msd6al to stock on a car and couldn't tell the difference.

Cats are required for mot from circa 1993. My old k reg brooklands doesn't have them. Think it was around cut off date. Lambdas won't be worried.

NGK 6 are fine. high tuned rv8s can prefer 7s when worked hard

As a wise man once told me, "You can have power, reliability or cheapness; but you can only have two of them"