Fresh Engine Build Thoughts

[Chriszz11]

Hello Everyone! I recently built a new engine for my 99 cobra that I don't think is running as well as it should. It is an 11.5:1 Compression 5.3 BBS with fox lake stage 3 ported 03 cobra heads, A set of custom grind Bullet racing cams 242/237 and set to 112 LSA, Sullivan fuel injected intake with stock fuel rails and 47lb injectors, Stock throttle body and a custom home made intake tube to the Lightning 90mm MAF, BBK Long tube headers, BBK Catted H-pipe, Borla Stinger cat-back, All accessories are functional as well. Anyways I had it tuned the other day, and it made 385hp and 344tq on a mustang dyno. I thought these numbers were pretty low and the graph looks odd to me, the horsepower peaks around 6700 and holds flat to redline and never falls off. I cant help but feel that this motor has more in it in the top end, but for some reason doesn't want to make power up there. Any Thoughts? Thanks in advance!

 

[01yellercobra]

What fuel are you running? Whats the timing set at? Don't forget Mustang Dynos tend to read on the low side. I'd get it out to a track to see how it runs.

 

[Chriszz11]

I'm running 93 in it right now. My tuner said timing was set max at 23* I believe. It isn't so much the peak number that is bothering me as it is that the power flattens out to redline from only 6700. It never drops off, but i thought it would peak at a higher rpm given the mods i have. Could the stock TB be holding me back in the top end? I want to go to the track, I'm just afraid of breaking my transmission, being that it's the stock tranny and it's my daily.

 

[biminiLX]

Choking it with stock TB and cats and possible MAF meter.
Easy power with changing those header collector ball/socket to a less restrictive design.
You have good compression with solid heads/cams/intake.
It's all about combination, so fix the TB forward and headers back, and remember it's an air pump.
Good luck.
-J

 

[Chriszz11]

Thanks! I'm trying to get more active on the forum. How much power is a good set of headers worth over the ones i have now? I was afraid of the cats impeding flow but wasn't sure how much power it would cost, I only put them on so I wouldn't smell like exhaust after every time i drive it.

 

[SID297]

Choking it with stock TB and cats and possible MAF meter.
Easy power with changing those header collector ball/socket to a less restrictive design.
You have good compression with solid heads/cams/intake.
It's all about combination, so fix the TB forward and headers back, and remember it's an air pump.
Good luck.
-J

This. You're strangling it.

 

[01yellercobra]

Are the cats really that restrictive though. I've made over 600 with high flow cats. Personally I prefer to keep them on of possible.

The stock TB could be an issue. I ran my stocker on my 5.3L. But I had a centri shoving air through it.

 

[Brutal Metal]

Are the cats really that restrictive though. I've made over 600 with high flow cats. Personally I prefer to keep them on of possible.

The stock TB could be an issue. I ran my stocker on my 5.3L. But I had a centri shoving air through it.

Yeah but you had Forced air going into your motor from the supercharger, oem cats are restrictive N/A. And yeah I'm still on the stock throttle body and intake on my 99. The factory 99-01 TB and intake have supported crazy power with turbos, 900+.

 

[Brutal Metal]

And OP you can safely run 27-28 with 93 pump N/A, your leaving HP on the table at 23. And also that Lightning MAF is DONE at about 400RW, what was your voltage and counts with it?

 

[Chriszz11]

I'll datalog tomorrow and let you know on the counts, I don't remember exactly what they were. We tried adding more timing and it didn't gain anything so we backed it back off again. It might have been more than 23 but I'm pretty sure it was close to it. I was told the LMAF was good to 500, but now I'm not sure. Haha

 

[01yellercobra]

Yeah but you had Forced air going into your motor from the supercharger, oem cats are restrictive N/A. And yeah I'm still on the stock throttle body and intake on my 99. The factory 99-01 TB and intake have supported crazy power with turbos, 900+.

I agree on the OEM cats. But hasn't there been posts of mid pipe with high flow cats being within a couple horsepower of an O/R set up? It's been a while since I looked into it. He says he's running an aftermarket mid pipe so I would think they're high flow.

That's why I said I had a blower on my set up. And that's why I never swapped it.

 

[Chriszz11]

I datalogged today and My mafs read 972 at it's highest.

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[shurur]

5.0 strokers are making 400 rwhp.....

hi flow cats don't hurt much at all.
there is a thread or two about it in corral and maybe svtp.

exhaust valves can be opened up. to near the diameter of the intake.
maybe larger diameter exhaust..although I have a article showing the opposite.

If you haven't already, I'd PM na svt to comment in this thread.

 

[Chriszz11]

It won't let me send a pm to na svt for some reason. Would you mind doing that for me?

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[01yellercobra]

When you had the cams ground did they say what RPM range they're good for?

FWIW, when I ran my BB/S in N/A form it made 326rwhp and similar torque. That was with stock 03 heads, 9.5:1 compression, Ford GT cams, stock 01 intake, and the timing was in the mid 20's. I ran it on pump gas and I only spun it to 6500.

I know of another set up that was a 3V engine. It made 430-435rwhp. But it had ported FRPP heads, custom cams, FRPP intake, 12:1 compression, and E85. I don't know his RPM range though.

As for only hitting 972 counts I'd say you have some room left. You could always try an O/R pipe just to see what happens.

 

[Chriszz11]

I appreciate your post, it's weird because on a stock Cobra with the Sullivan intake it doesn't start making good power until over 6k and keeps going up to redline. With your setup I have much more aggressive intake and cams plus ported heads and higher compression, so I would think I should rev more than 200rpm higher than you. Although I bet yours made a great street car with a great torque curve haha. When I had my cams ground I told them what rpm I wanted, they told me what I should use and then I added a bit more duration and a wider lsa. They said 235/235 with 111lsa, so I thought mine would be great for the rpms.

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[98 Saleen Cobra]

What are the cams degree'd at?

Also what size primary headers? That compression, intake, cam, head setup imo needs some bigger primary's.. I could be wrong though.

 

[Chriszz11]

What are the cams degree'd at?

I have them set at 112 right now.

The headers are 1 5/8" primaries

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[Chriszz11]

So I just cut my 90 degree elbow that was in the fender off so it's a straight shot into the intake. The pipe that goes into the fender is only 3.25" or 83mm so it's definitely still too small, I ordered a 101mm maf adaptor for my air filter to attach to in the fender. With the 3.25" pipe on it, I am now pegging my lightning maf...

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[na svt]

What are the cam lobe centers? I would bet money on the intake lobe center being too low.
The durations are not good IMO, too much intake duration and not enough on the exhaust side.
The headers are too small, you need 1 3/4" or 1 3/4 to 1 7/8 stepped primaries.
The TB is fine.
A 90MM maf is plenty.

A BB/S with that much compression can make 450/400 on a dynojet with SAE factoring while staying under 7000rpm.