power gains from 4.0 top end build?

[Super mud]

I've been wondering what can be built out of a 4.0 on the top end for any reasonable gains. Im not considering it any time soon since i got other stuff fix on my 87 which runs great on a 88 motor and tranny with exaust, cai, and some sensor adjustments/tune. Though I like to know whats possible and all the extra details involved involved with this motor. I do find it most enjoyable stomping 4 bangers and full size trucks with my xj on 31s also lmao.
Strokers are the way to go but I was thinking a HO head and 99+ intake swap, filled by a little taller cam and compression increase could yeild some good gains along with extra goodies on the outside. 8.8:1 I believe is stock and I've heard a thinner mopar head gasket and head deck of .30-.40 can get close 9.5:1. I estimated around 250 hp and a good bit of torque. So anybody have any opinions or know any previous threads/builds?

 

[Dr. Dyno]

Strokers are the way to go but I was thinking a HO head and 99+ intake swap, filled by a little taller cam and compression increase could yeild some good gains along with extra goodies on the outside. 8.8:1 I believe is stock and I've heard a thinner mopar head gasket and head deck of .30-.40 can get close 9.5:1. I estimated around 250 hp and a good bit of torque. So anybody have any opinions or know any previous threads/builds?

It sounds like you've got things pretty well sussed out but it'll take quite a lot of work to get 250hp out of the 4.0 without stroking it. I guess you must have seen this list from my site:

Tuning Stages:

Stage 1 (220hp @ 5000rpm, 262lbft @ 3750rpm) No internal engine mods.

1. Induction: FIPK with Powerstack cone filter, bored 62mm TB, bored 62mm TB spacer.
2. Exhaust: 2.25" exhaust system, header, high-flow cat and muffler.
3. Ignition: High performance plug wires and plugs.
4. Hypertech Power Programmer III (OBD II), Kenne Bell Optimizer II (OBD II), or JET stage 2 (OBD I & II) with 180* thermostat.
5. Replace stock clutch fan with electric fan.
6. Ford Racing 24lb/hr injectors.
7. Relocate IAT sensor to cold air intake.
8. MAP sensor input voltage adjuster.

Stage 2a (240hp @ 5100rpm, 284lbft @ 3500rpm) Low/medium rpm torquer engine

9. Ported stock cylinder head.
10. Raise CR to 9.1:1
11. CompCams 192/200 degree cam #68-115-4.
12. 1.7 ratio roller rockers.

Stage 2b (257hp @ 5300rpm, 290lbft @ 4000rpm)

9. Big valve ported head.
10. Raise CR to 9.5:1.
11. CompCams 206/214 degree cam #68-231-4.
12. Raise rev-limiter to 5600rpm.
13. 2.5" Exhaust system.
14. Strengthen bottom end: ARP 112-6001 rod bolt set, magnaflux and shot-peen connecting rods, balance rotating assembly.
15. Upgrade oiling system: high volume oil pump, oil cooler.
16. Upgrade cooling system: aluminium radiator, high-flow water pump.
17. 3.55 axle gears + 28" tires with automatic and manual transmission.

Stage 3

4.6L-5.0L stroker engines: 240-344hp, 303-384lbft depending on build specifications.
Kenne-Bell 5.5psi intercooled supercharger kit: 45% more hp, 53% more torque.
505 Performance 6.0psi turbocharger kit: 44% more hp, 47% more torque.
Nitrous Express (75hp) N2O injection kit: 76hp/117lbft gain.

 

[Super mud]

yea I've actually seen ur site a couple times. Have you tested the newer intake manifold at all with the cam and head upgrades? I used to always hear of a 20hp increase but JP tested a bunch of 4.0 myths and said it wasn't a gain since the motor already had enough flow for stock cam and internals or something.
those seem like decent gains (stage 2) considering thats still pretty mild build?
how tall are the cams you used compared to stock and something radical

 

[Dr. Dyno]

I did the newer intake manifold swap last year on my 4.6 stroker, gaining 2rwhp/4rwtq at the peaks and ~5rwtq over most of the rpm range. I also gained ~1mpg fuel mileage so the $53 manifold quickly paid for itself.

 

[Super mud]

Well 1mpg more is at least something. I recently heard about precision injectors and their benefits and might be looking into those eventually too. I've heard funny things about them clogging at first but the problem is logical and fixable from what i've heard.

 

[DieselSJ]

Stage 2b (257hp @ 5300rpm, 290lbft @ 4000rpm)

9. Big valve ported head.
10. Raise CR to 9.5:1.
11. CompCams 206/214 degree cam #68-231-4.
12. Raise rev-limiter to 5600rpm.
13. 2.5" Exhaust system.
14. Strengthen bottom end: ARP 112-6001 rod bolt set, magnaflux and shot-peen connecting rods, balance rotating assembly.
15. Upgrade oiling system: high volume oil pump, oil cooler.
16. Upgrade cooling system: aluminium radiator, high-flow water pump.
17. 3.55 axle gears + 28" tires with automatic and manual transmission.

That is pretty much our race setup right there...we have a little more cam and a touch more compression and slightly higher rev limit. No need to go with aluminum radiator - never went over 210 all season with a 2-core copper/brass and 2 stock late-model electric fans.

 

[Super mud]

That is pretty much our race setup right there...we have a little more cam and a touch more compression and slightly higher rev limit. No need to go with aluminum radiator - never went over 210 all season with a 2-core copper/brass and 2 stock late-model electric fans.

For prerunning? If so 210 seems very good/stable for the temps for racing.

 

[DieselSJ]

For prerunning? If so 210 seems very good/stable for the temps for racing.

What about pre-running? I'm just saying that there is no reason for a high-dollar aluminum radiator. A 2-core copper/brass cools 250hp just fine under race conditions, which are much more demanding than pre-running or street use.

 

[yossarian19]

I did the newer intake manifold swap last year on my 4.6 stroker, gaining 2rwhp/4rwtq at the peaks and ~5rwtq over most of the rpm range. I also gained ~1mpg fuel mileage so the $53 manifold quickly paid for itself.

Your claim and JPMagazine's disagree. They claim a 5HP loss on one project 4.0, measured by dyno. I suspect the difference is in the increased displacement of a stroker vs a stock-ish 4.0. Care to comment? Can both of you be correct?

 

[american_zero]

Many people also do not tweak the fuel when they install the newer manifold. Either through the fuel pressure regulator or a map sensor adjuster. Something to consider when evaluating peoples claims.

 

[Talyn]

That little bit of change won't require the fuel curve to be changed.

 

[DieselSJ]

Your claim and JPMagazine's disagree. They claim a 5HP loss on one project 4.0, measured by dyno. I suspect the difference is in the increased displacement of a stroker vs a stock-ish 4.0. Care to comment? Can both of you be correct?

I think the big problem is that people just bolt them on and expect them to work. It isn't that simple. I had to do A LOT of work to the head and the intake to get the ports to line up correctly. After going from early to late on our 4.0 in the racer, I saw an increase in the VE so I know it is making better power than with the early style intake.

 

[Dr. Dyno]

Your claim and JPMagazine's disagree. They claim a 5HP loss on one project 4.0, measured by dyno. I suspect the difference is in the increased displacement of a stroker vs a stock-ish 4.0. Care to comment? Can both of you be correct?

If anything, the HP gain should be bigger on a 4.0 than on a stroker. I suspect that JP magazine didn't tune the engine after they swapped manifolds whereas I did. After I did my manifold swap, the engine ran lean and had a slight low rpm miss so I had to raise the MAP sensor input voltage with my MAP adjuster to correct the A/F ratio. The engine ran noticeably better after the fuel enrichment and felt stronger than ever. Not only that, I'm also getting the best gas mileage I've ever had even compared to my old 4.0 (which was still strong & healthy).
For me, the manifold swap was a win win deal.

 

[yossarian19]

So from what you guys are saying, the discrepancy is the result of bolting it on and calling it a day vs port matching, tuning the MAP and putting some more TLC into the project.

Thanks!

 

[DieselSJ]

So from what you guys are saying, the discrepancy is the result of bolting it on and calling it a day vs port matching, tuning the MAP and putting some more TLC into the project.

Thanks!

Yep. Kinda like the old days where someone would throw an aftermarket intake and carb onto their V8 and expect it to perform without any additional tuning. Then they complain that it sucked. The difference is in the details.

 

[gradon]

I port matched mine, smoothed the walls a bit, and ground down the injector bosses that get progressively larger from outer to inner cylinders.

 

[american_zero]

That little bit of change won't require the fuel curve to be changed.

If anything, the HP gain should be bigger on a 4.0 than on a stroker. I suspect that JP magazine didn't tune the engine after they swapped manifolds whereas I did. After I did my manifold swap, the engine ran lean and had a slight low rpm miss so I had to raise the MAP sensor input voltage with my MAP adjuster to correct the A/F ratio. The engine ran noticeably better after the fuel enrichment and felt stronger than ever. Not only that, I'm also getting the best gas mileage I've ever had even compared to my old 4.0 (which was still strong & healthy).
For me, the manifold swap was a win win deal.

I've seen the same thing from a few other people online. The change is significant enough that it's necessary to add a little fuel to make use of the air. While it may "only" add 5 peak hp, the gains across the board are probably pretty substantial.

 

[Dr. Dyno]

So from what you guys are saying, the discrepancy is the result of bolting it on and calling it a day vs port matching, tuning the MAP and putting some more TLC into the project.

Exactly. I port matched my intake and also ground the injector bosses to smoothen the airflow.

I've seen the same thing from a few other people online. The change is significant enough that it's necessary to add a little fuel to make use of the air. While it may "only" add 5 peak hp, the gains across the board are probably pretty substantial.

Yeah, while the peak HP gain is small, the biggest torque gains are lower down the rpm range where you operate the engine for the longest time and feel the difference.

 

[Talyn]

I've seen the same thing from a few other people online. The change is significant enough that it's necessary to add a little fuel to make use of the air. While it may "only" add 5 peak hp, the gains across the board are probably pretty substantial.

Even if you add a map adjuster it isn't going to do crap for where most of the change occurs. At that range the engine will be mostly in closed loop and will be maintaining 14.7 AFR no matter what you do to the map sensor. Further more the stock AFR is pretty rich at WOT /open loop anyhow. Whom ever you heard this from is wrong.

 

[Dr. Dyno]

Even if you add a map adjuster it isn't going to do crap for where most of the change occurs. At that range the engine will be mostly in closed loop and will be maintaining 14.7 AFR no matter what you do to the map sensor. Further more the stock AFR is pretty rich at WOT /open loop anyhow. Whom ever you heard this from is wrong.

Depends on which model year you have as the OBD II engine computers behave differently, and the '00+ computers are locked into a 14.7 AFR at WOT from off idle to 2300rpm. The MAP adjuster is most effective on Renix and '91-'95 HO models, works fairly well on '96-'99 models, and is a waste of time on the distributorless ignition '00+.