What Should I Rev Too?

vpap1 · Jun 24, 2012

i have a fresh 10 to 1 347
stage 2 tfs cam, installed dot to dot
track heat 170 cc heads and intakes
stock igntion with upgrades plugs wires, tfi module and coil
shorty equal length headers 2.5" non cat h pipe flowmaster exhaust into 2" tail pipes

what should this combo make power too ?

I only made power to 5250 rpm and it was low on power

what could cause this, cam and intake should be able to rev to 6000 rpm

could it be my ignition preventing, dyno graph looks like it starts to break up at 5000 rpm

are the tail pipes that much of a restriction?

base timing is at 8 degrees, but has been tuned with a 4 bank and at idle with spout in has 18 at idle = 950 rpm and total at about 31 degrees at 3400 rpm

i gave it to 13 degrees at base to see if it mattered and it did not ping but still didn't feel up on power

anythoughts?

a91what · Jun 24, 2012

For what its worth, i think your exhaust is restrictive. Think of the engine as a funnel, you want velocity. The biggest part at the filter and slowly step down in size all the way to the intake runners. When the exhaust is leaving the engine it works in reverse, headers feed your crossover, then they feed the tail pipes.

vpap1 · Jun 24, 2012

i gotcha, i can do a cat back or do you reccomend more? What would nect restriction you think might be?

Gearbanger 101 · Jun 24, 2012

I personally think your problems are elseware. A stock diameter cat back is capable of suporting well over 400hp. What are your plugs gapped at? "breaking up" at higher RPM sounds more ignition related to me.

89stang1 · Jun 24, 2012

Gearbanger 101 said:
I personally think your problems are elseware. A stock diameter cat back is capable of suporting well over 400hp. What are your plugs gapped at? "breaking up" at higher RPM sounds more ignition related to me.

i agree with brian you should make power to 5800rpms....you really went conservative with timing your holding back power there for sure. I dont think thats why your breaking up tho, im leaning towards ignition too tfi or pip sensor.

vpap1 · Jun 24, 2012

the car was dyno tuned to 282 rwhp by dez racing
they installed the plugs and the 4 bank chip- all timing is adjusted thru there
i agree with ignition it is the only stock part still on the car- how can i diagnose a weak coil or tfi module?

a91what · Jun 24, 2012

Once again i never run anything less than 21/2 for exhaust it sure wont hurt to get the exhaust velocity working especially if your revvin it high. But no it wont cause your engine to "break up". Nor did i say it would. jrichker has a link for that.. i would post it if i could find it.

5.0Droptop · Jun 24, 2012

Rev to infinity and beyond!

5.0Droptop · Jun 24, 2012

Sounds like its running out of fuel to me. What fuel pump you have?

Did the dyno tuner use a wide band to check the air fuel ratio?

My 347 ran 14-16degree base timing with twisted wedge heads. Holly systemax intake. Tfs 2 cam etc. it made 365/434

I had fuel issues running 24# injs. I had to go to 30# injs

Gearbanger 101 · Jun 24, 2012

a91what said:
But no it wont cause your engine to "break up". Nor did i say it would.

I guess it's a good thing nobody accused of doing that then.

88LX5.Oh · Jun 24, 2012

What size injectors and fuel pump are you running?

vpap1 · Jun 25, 2012

ihave a 255 lph fuel pump and 30# injectors

the A/F ratio looks very smooth on the dyno sheet at 13:1 maybe a touch lower

i can cut the pipe coming out of the muffler and see if it helps and tac on some 2.5" pipes- i prob will do this anyway, they are currently going through the rear bumper, i know classy

dez is a legend around here and dont think its his tuning, base timing is low but the chip adds a boat load at idle and sounds right at around 32 degrees at 3400 rpm or so

well its getting its air, how to check to see if its getting the fuel and spark required?

2000xp8 · Jun 25, 2012

While your exhaust may not be optimal, it is NOT costing you 100rwhp.

I'd also be concerned a guy that tunes a car to a hp number that low and rpm that far off and thinks it's ok to send it out the door with a finalized chip in it.
Should of told you to come back when the car was right or offered to fix it for you (at a cost of course). Seriously, who tunes a car that is messed up? Maybe he's legend for newer cars, but those guys rarely know what the hell they are doing on foxes.

Aftermarket ignition parts for the fox are pretty much useless, so don't go thinking an msd box or coil is going to help, stock parts are better.
Find your problem with your factory parts.

That setup doesn't need a tune either. The tuning market on a fox is such a racket, it's 95% about money, 5% about tuning.

As for finding your problem, start by putting the stock coil and tfi back on, every single aftermarket tfi is a piece of crap same goes for the coil.

Second, what springs are on the heads? Could very well be you are floating valves.

srtthis · Jun 25, 2012

what makes you think its out of power at 5250? thats a very important number when calculating horsepower

vpap1 · Jun 25, 2012

5200- 5300 its goes up and down a bit and at 5375 ish it falls off some according to the dyno sheet

the car came with a stock distrib with a dyno mod tfi and screamin demon coil, i do not have any other pieces to swap out good to .600 lift

Trick flow said that the springs on the track heat heads are good to 6000 rpm and good for my combo. whats the best way to check with out disassembling the heads or taking them off

srtthis · Jun 25, 2012

you can get a spring force gauge and check them on the head.

as for the RPM. 5250 is where ALL dyno sheets if the dyno is right will have the HP and torque cross. which is why i asked.

vpap1 · Jun 25, 2012

srtthis said:
you can get a spring force gauge and check them on the head.

as for the RPM. 5250 is where ALL dyno sheets if the dyno is right will have the HP and torque cross. which is why i asked.

i understand i just can't be happy with the research it did to build something with 320 ish rwp and fall short 40 whp. If i need to learn to drive it again so be it, i just need to find the hp, the revs to where i should be and achieve at least the mph ball park to know it runs as it should.

i've heard everything from issues with valve springs, exhaust, mis degreed cam , ignition to plug gap.

Guess i start with the cheapest testing first ...

cutting the 2" tail pipe so there is no restriction

check plug gaps- for my motor where abouts should that be i see at 40-45 for alot of 347's

valve last sounds fine but i can re adjust

compression test

and go from there i guess

vpap1 · Jun 25, 2012

are 6.700 " pushrods proper for my set up, same ones that came with the top end kit ?

Noobz347 · Jun 25, 2012

Your exhaust is not the problem.

I tend to think that your breaking up problems are the result of an ignition malfunction. New wires don't mean GOOD wires... particularly at the top of the RPM range. Look at teh dizzy, wires, TFI, cap and rotor AGAIN. If you're breaking up then it's either fuel or spark (sometimes cam but that would have symptoms at more than just the top), and it doesn't sound like you're having fuel issues.

I also think that those tiny heads are going to prevent you from making that final number that the rest of the combo appears able to provide.

Were it me, I'd be looking at changing the heads and getting a custom cam once the other problem were sorted. The combo in the first post appears cobbled together.

You don't mention what MAF or TB you're running. I would hope that if that were malfunctioning that the tuner would know. Hopefully this guy is not a, "Hack".

vpap1 · Jun 25, 2012

i still think even though the heads are small and the cam is off the shell i should see 320 rwhp

plenty of people making that kind of hp with those heads - id love to go bigger but budget- well there is no budget at this point- just wanna make what i got work first

wires are msd 8.5 mm and plugs are autolites 3924's they are new but i will check them, how do i check the tfi and coil? can i use a multimeter?

80 mm maf and 75 mm tb may is c l and tb is trickflow

this guy is deff not a hack- i did notice that 1 of the cap retaining clips is missing and the cap sits right but im sure isnt totally secure, would this be a cause?

i believe its the ignition but its only at high rpm, still runs smooth and pulls great, dyno graph is smooth as silk till that 5300 rpm point

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