Performance 4.0 down on power?

[limit_explore]

What's up guys, just looking for some opinions here. Be warned, it may be bit of a read!

I know a lot of the guys who have built performance based 4.0 OHVs might be gone from the forums but hoping there are some still lurking around!

engine build is as follows:
1991 4.0 ohv
.030 over pistons
422 cam
supersix motorsports ported 98tm heads with 988 valve springs
ported lower intake
ported fuel rail
ported later model plastic intake (96-97?)
66mm bbk throttle body
24lbs injectors with adjustable fuel pressure regulator
jba headers
2.25" from collectors to single 2.5" exhaust minimal bends single chamber muffler
screamin demon coil
taylor low ohm wires
tr55gp plugs
running 112 octane Sunoco
auto trans, dyno was done in 3rd gear with T/C locked (only a 2hp difference between locked and unlocked)
using a megasquirt ecu (mspnp2 from DIYautotune) and yes I have control of timing advance.

Heads were milled .010-.020 and the block was decked but an unknown number (block was rebuilt but not ran before I bought it)
when I measured pushrod length they came up about at 5.437" which is .040" shorter then a factory push rod measured (5.476). This was slightly confusing because the comp cams 422 is supposed to need a longer push rod (5.550"), but it was determined the measurement must be reflecting the block being decked and heads milled. so we used stock pushrods to add .040" preload to the lifter. There is no noticeable valve train noise.

I took the truck to get tuned on a dyno (hub dyno) and found the truck appears to be about 50-90hp lower then expected at the wheels. With all the mods it is my understanding the engine should make between 200hp and 250hp at the wheel. The tuner has the truck running good, however it got to a point where adding timing/fuel was no longer making power. He felt the truck needed more air in.

I'll attach my dyno sheet. truck made 157hp and 210lbs torque, that's almost stock rated hp at the crank. When I got home I did a hot engine compression test and found the engine had 170psi average across all 6, with a high of 174 and low of 169, most cylinders reading 170-172psi which seemed low since the heads (98tm) were supposed to add around a point to the compression ratio making it 10:1, not including the .010-.020 off the heads and however much was removed from the block.

At this point we are thinking possibly cam timing is off. I did not "degree" the cam, I installed a new timing set (ITM brand) and lined up the dots.

What does everyone else think?

 

[limit_explore]

Pulled the engine out today. It’s easier to degree the cam on a stand plus the oil pan/rear main seal were leaking.

Took a quick check of the timing, cam and crank dots line up.

Degree wheel comes in on Tuesday, I plan to degree the cam to Compcams specs, and then measure lift to make sure I actually got a 422, and it wasn’t miss packaged.

After that I will re check the push rod length and post the results.

I am tempted to pull the heads and measure for static compression ratio, but don’t really want to waste all the new gaskets on it.

 

[superj]

i cannot help at all but i am reading along because this is interesting to read about

 

[Blmpkn]

112 octane is... the definition of overkill isn't it? 10:1 would be happy with 91. All 112 is doing is leading to an incomplete burn, less power, more carbon buildup.

 

[limit_explore]

112 octane is... the definition of overkill isn't it? 10:1 would be happy with 91. All 112 is doing is leading to an incomplete burn, less power, more carbon buildup.

I would agree, there were a couple reasons for running 112was that the compression ratio should be closer to 11:1 with the amount of material removed from the heads and block.

Another reason is the truck is built for off road racing so the lead in the fuel should help in the high summer temps.

Also the truck sits for periods of time between races, and when getting fixed. Californias ethanol fuel (91) goes bad pretty quick and I have seen a difference with the old motor between 6 months of the truck sitting, and a fresh tank of fuel.

 

[gaz]

@limit_explore
The only move on your list that I do not agree with is the 24lb injectors; the stock injectors should support up to 300hp.

If you are on an automatic transmission, you can factor a 20-25% power loss from it... that drops a crank 240hp to at least 200hp wheel or a 200hp becomes 160hp on the Dyno measurement.

While I agree that you compression ratio may be close to 11:1+/-, I will and have used pump 91-93 octane up to 13.5:1 C/R; 13.5:1 is the number I was taught as the highest to consider running on pump premium. My 2.9l Ranger is sitting right around 12.5:1 and has never had a ping, pang or pong on pump premium.

Did you have a valve job performed when you had the work done in the heads?

I expect that your exhaust may be the culprit. A 2.9l with all your listed components/processes using a 2.5" exhaust will run very well but it was recommended by both my machinist and exhaust manufacturer to use dual 2" or dual 2.25" with a 4.0l, matching your performance list changes.

Simple way to check, since you went to 2¼" from the collectors...remove the 2.5" section and try it

 

[limit_explore]

@gaz how much horsepower does your 2.9l make with similar mods? And I presume it’s manual transmission?


My injectors are currently at 75% duty cycle at 160rwhp, so they aren’t too big, but I was hesitant too. It was recommended by multiple dyno shops before I got on the dyno due to my expected 200ish rwhp

yes Tom at supersixmotorsports did do a valve job when he had my heads apart for porting. He also installed the behive springs.

as far as exhaust goes, pulling off the 2.5 at my y pipe is totally doable. And something I could do at the dyno shop as a test.

 

[limit_explore]

So far I have found with my cam timing set installed “straight up” the cam comes in at 11 degrees advanced. Each tooth on the cam gear is approximately 9 degrees so I will retard the cam one tooth and see what that does.

i performed a leak down test just to see if I was loosing compression, almost all cylinders were at 95psi out of 100 except one cylinder was holding 100psi

pushrods still measure out to 5.42x, which still seems really short to me.

 

[JoshT]

supersix motorsports ported 98tm heads with 988 valve springs

In all my years around various Ranger forums, I think you are the first I've seen actually using Super Six Motorsports for anything. Hadn;t thought about them in years. They are actually local to me, and I went to tech school with one of the sons. Back then I thought about going to them for some performance stuff, but never did it.

I expect that your exhaust may be the culprit. A 2.9l with all your listed components/processes using a 2.5" exhaust will run very well but I was recommended by both my machinist and exhaust manufacturer to use dual 2" or dual 2.25" with a 4.0l, matching your performance list changes.

Simple way to check, since you went to 2¼" from the collectors...remove the 2.5" section and try it

That would be interesting to see. I'm wondering if that might be partially to blame for the under whelming performance of my 5.0 swap. I've replaced the manifolds with torque monster knockoffs which freed it up some, but I've got dual 2.5" feeding into single muffler and single 2.5" exit. Dual 2.5 should be enough for the power levels I make, the single 2.5 part might be an issue though. I was only meant to be temporary. I'll be getting it fixed soon after getting the suspension adjusted.

 

[limit_explore]

In all my years around various Ranger forums, I think you are the first I've seen actually using Super Six Motorsports for anything. Hadn;t thought about them in years. They are actually local to me, and I went to tech school with one of the sons. Back then I thought about going to them for some performance stuff, but never did it.

I don’t know if that’s a good thing or bad thing. Haha. I had called him and Tom Morrana and liked not having to send heads to Canada. He sounded knowledgeable and had built a few of the 7s/sx desert race motors so he had an understanding of what I was looking for. He also had done work for the old Bama tune guys

 

[JoshT]

It's not a bad thing. They target a niche market, but seem to be good at what they do. Most people aren't going to invest that much time and money in a V6 unless they have a good reason to do so. Around here most would opt for minor internal upgrade and bolt-ons (intake, exhaust, forced induction) for the V6, or to engine swap.

If I were messing with a Ford V6 again, I'd much rather give my money to Super Six than Tom Moana.

 

[gaz]

@limit_explore
BAD TIMING
Off by a whole tooth, holly crap...you may have dodged the mother load bullet; with those small dish pistons/fast burn heads those valves are close; if you didn't damage anything, you dodged a heck of a bullet ..)

BOTH TRANSMISSIONS
I've used that 2.9 with both an A4LD (in BII) and a 5 speed (in Ranger) but I have never put it on the dyno. I judged the performance by how much work it could do verses how much fuel it uses. I can site specific/graphic examples if desired ..)

OUTPUT
When I spoke with my machinist about this, his best guess was in the 210+/- at the crank, then factor in transmission loss. He suggested the following:
1) +20hp, head/intake flow bench P+P
2) +20hp, custom cam
3) +20hp, headers free flow exhaust
4) +10%, complete bottom end balance
Fortunately, it is much simpler to get more base timing advance with the EEC-IV 2.9l, verses the "new and improved" DiS 4.0 with EEC-IV; with the 4.0 I am limited to 4° built into the cam and whatever the Hypertech chip can manage.

YOUR 4.0 OPTIONS
-If using the dual 2¼" exhaust doesn't get your results, then perhaps slip in the stock injectors and retest. With the setup you have on this 4.0, I expect 230+/- @ the crank, perhaps a little more or a little less depending on how happy everything is together.
-you could always swap in a set of Ford SOHC 4.0L flat pistons, if you want another easy 15hp
-not knocking THE Megasquirt but the Ford 93-94 SFI-MAS-EDIS California PCM will also net an addition 10% efficiency over the Federal version. All that you would need is a 93-94 California PCM+harness

If all things panned out halfway decent, your current 160 @ the wheels could realize 200-210 @ the wheels:
• free floating rocker arms
• stock injectors
• true dual 2¼"
• +15hp flat top pistons
• +10% SFI-MAS-EDIS PCM

 

[limit_explore]

@gaz
what really bothers me about the timing being off is the damn dots are lined up perfect. But when I degree the cam it’s off by a tooth. Leak down shows no signs of valve damage luckily but the heads are coming off anyway because I ordered sohc flat tops (actually before you mentioned it haha). I plan to properly cc my heads, along with measuring piston to deck height

when inputing the measurements it appears my DYNAMIC ratio is 8.8:1 static is 10:1, and that’s using stock measurements for head cc (98tm are 48cc) and dimensions of piston to deck clearance found on here. So may be slightly higher with my heads and block milled.

when using sohc pistons in that equation I come up with about 12.5:1 static and 10:1 dynamic. So that should definitely add some pop to this thing. especially if the heads and block were milled like the pushrod measurements show.

Since it’s all torn down I ordered material for the free floating rockers, I’ll machine those up on the lathe.

one of the reasons for going Megasquirt was total control over fuel and timing. Plus no one local to me would tune the factory ecm.

I’m fully not convinced the smaller injector would yield more power since I have a fuel table controlling how much is sprayed. Pretty sure going down to a 19 would mean my entire fuel table would need to be remapped but it may be worth a try.

I will probably also order another set of 2.25” header bells and weld on a foot or so of straight pipe and do a pull with that to see if there is any restriction there

 

[gaz]

@limit_explore
It is possible that the cam has timing built into the grind, my custom 4.0l cam will have 4° of advance in the grind; perhaps a call to the manufacturer is in order...A WHOLE TOOTH is definitely too much!!

The larger injector could be passing too much fuel, running a rich can be good and bad. Either way, other than the time needed to swap them, it is a free troubleshoot play.

I believe that the BEST money spent is in fuel management but if I can safely accomplish my fuel economy objectives using the stock PCM, I am content. I too am intrigued with the Megasquirt options ..)

Since you have access to a machine shop, you could also machine ½ a set of 2.9l adjustable rockers for use in your 4.0; six of them will align correct, the other 6 need like a 1/16" removed from the side of the rocker. I mention this as it is a great work around to yield a fully adjustable valve train and the change will effect the dimension of your rocker arm spacers

 

[gaz]

I am curious what your goal(s) are with this build ..)