7afe loss of power Options

[Toynado]

hi all, i got a qiuck question, i got a stock 7afe with 4 into 1 headers and a performance filter and 17inch wheels, on sat we had a dyno day and my car made 76 kw at the wheels and 147 nm torque, it makes max torque at about 4000rpm and at max kw just after 4500rpm. there after it doesnt do much in the way of speed, i struggle to reach 195km/h my my friend with a stock 4age motor passes me like i'm standing still, the motor is newly rebuilt, question is why am i being creamed. the car pulls strong up untlill 3rd gear but when i put it in 4th i'ts all show and no go. is the dyno figures about right or not the workshop manual says it does 86kw dont know where the measure it though.

[Bitter]

the 86kw is probably at the crank, so 76 to the wheels isnt too bad. thats about 100whp and 108 lb/ft.

thats actually pretty good for a stock 7afe! advance your timing a few degrees to see if that'll bring your torque curve to peak a little lower again, or you can build up and raise compression some for more power across the powerband, however i dont think the price of the work would equal the gains. the timing advance is free, just run a higher octane fuel.

[97lestyousay]

my my friend with a stock 4age motor passes me like i'm standing still,

What kind of 4age I have a 16 valve in an 88 ae92 and my stock 7afe would
give it a good run if not beat it. Silvertop, blacktop, or 4agze would be a different
story.

[Toynado]

the 86kw is probably at the crank, so 76 to the wheels isnt too bad. thats about 100whp and 108 lb/ft.

thats actually pretty good for a stock 7afe! advance your timing a few degrees to see if that'll bring your torque curve to peak a little lower again, or you can build up and raise compression some for more power across the powerband, however i dont think the price of the work would equal the gains. the timing advance is free, just run a higher octane fuel.

i,m running the highest octane fuel available, which is a 95 lead replacement petrol. or can i run a racing fuel of 102.9 can it maby be that my exhaust is to big i'm using a 57milimeter freeflow exhaust.

[Toynado]

the 86kw is probably at the crank, so 76 to the wheels isnt too bad. thats about 100whp and 108 lb/ft.

thats actually pretty good for a stock 7afe! advance your timing a few degrees to see if that'll bring your torque curve to peak a little lower again, or you can build up and raise compression some for more power across the powerband, however i dont think the price of the work would equal the gains. the timing advance is free, just run a higher octane fuel.

i,m running the highest octane fuel available, which is a 95 lead replacement petrol. or can i run a racing fuel of 102.9 can it maby be that my exhaust is to big i'm using a 57milimeter freeflow exhaust.

[Bitter]

well running higher octane without anything that needs higher octane does nothing. advance the timing to 15 degrees before top dead center and then go back to the dyno and see how it helps, if any. 2.25 inches (57mm) is a little large for a 7afe, 2 inches (50mm) might be a little more appropriate.

also, you might want to look at getting a wideband O2 sensor with guage and then some kind of tuning device like a safc2 so that you can tune the full throttle air/fuel ratio. you can pickup 3-5whp from that too.

as for the intake, if its all stock with just a filter, try something aftermarket or modify the stock airbox into a short ram. remove the tubing leading into the airbox but leave everything else alone.

This post has been edited by Bitter: Jan 31, 2007 - 4:30 PM

[playr158]

1st hint why u have no powar........it starts with the fact its a 7afe

[Bitter]

1st hint why u have no powar........it starts with the fact its a 7afe

100whp from a 7afe isnt too shabby tho especially considering all he added was a header and exhaust.

[GTS13]

Ok, here's a few suggestions. Adding headers that just lead into a stock exhaust isn't going to do anything for you. Finish off the rest of the exhaust with a 2" header back with high flow cat and muffler. If you've already done this then disregard it. Next, nothing about a 7AFE needs that high of an octane unless you turbo it. Try running a more moderate octane whatever is in the middle for you. As for advancing your timing? lol, not really the best idea. You probably just spent some money on rebuilding your engine and this isn't going to help you maintain it's condition. Now I also agree that if you're going to do the full exhaust you'll want an aftermarket short ram intake and make your own heat shield for it. Taking a look at your wheels I can tell you that with a 7AFE, height matters. If you have a 45 height tire you're gonna lose a little momentum, try a 40 height if you don't already have it. (Hypocritically I learned that one the hard way).
Lastly, you have to understand the engines with the F series head are made for low end torque so once you reach those higher gears you're sort of out of luck, there isn't a whole lot you can do about it. I recommend reading this spot over at Toysport and making any decisions for the future of your vehicle afterwards.

http://toysport.com/webpages/Techinfo/Engi...FE20Engines.htm

Hope all this helps.

This post has been edited by GTS13: Jan 31, 2007 - 5:46 PM

[Bitter]

advancing the timing does show nice gains for the money spent, which is nothing. on 89 octane the 7afe can safely run 15 degrees of base timing.

its a pretty widely accepted thing to do with the FE engines, the chamber design is very knock resistant.


if you dont understand what timing does and how it all works then just dont talk about it GTS13. timing is where NA power lies, even moreso than AF tuning. finding the right amount of advance or retard is what its all about, ask anyone who tunes engines and they'll agree.

[GTS13]

Wow, I'm not trying to knock anyone's methods, and apologize if I've offended anyone. In this particular case it can help gains (minimal as it may be), but for someone that has just rebuilt their engine you have to admit that there could "potentially," I'm not gonna say there will be, but potentially adverse effects in the future. If you wanna recommend someone do something you should probably go all out.
For example, if you're going to advance your timing there's more you have to do in preventative maintenance. You'll need colder sparking plugs because the increase in timing increases the end temperature of your spark. You'll have to run higher octane, in this instance he already does but not for any real given reason. Other things follow, you can cause internal engine damage if the proper procedures aren't taken to take care of your engine.
"Timing is controlled by the relationship of the position of the piston to when the spark occurs. If the ignition spark occurs too soon it can actually push against a piston traveling up the cylinder as it's compressing the fuel/air mixture. This causes detonation, lost power, much higher combustion temperatures as well as higher emissions and early internal engine part failures."

I'm pretty sure I understand timing, thanks though.

This post has been edited by GTS13: Jan 31, 2007 - 7:38 PM

[Bitter]

the risk of damage at 15 degrees base timing is pretty slim :lol: he's more likely to be in a car accident than to do engine damage with the octane of fuel he's running. also at 15 degrees and 95 octane he wont need to change plugs.

[GTS13]

I just wanted to make sure he knew everything before he did it. Trying to educate people lol. We cool Bitter?

This post has been edited by GTS13: Feb 2, 2007 - 2:24 PM

[rayneezy23]

1st hint why u have no powar........it starts with the fact its a 7afe

i read that the gt in one of the forums doesnt really make a difference in power as the st

[OOBE]

It's sad that my stock 599cc Ninja has more HP than my 7A in its stock form. :rofl:

[Bitter]

It's sad that my stock 599cc Ninja has more HP than my 7A in its stock form. :rofl:

nope, you're cranking out around the same crank hp as a 4afe but with about 40lb/ft less torque and a much more peaky power band. its your high gearing and low weight that makes it pretty quick. 5th gear is like 6:1 still :lol: and 1st is like 20:1!

[OOBE]

Well, a ZX-6RR, according to the specs "out there", has 118 horsepower to the crank. The 94-95 7A-FE has 110 horsepower according to the specs "out there" and 115 ft/lb of torque. When I dynoed my bike in VA to compare it to my buddy's modded GSX-R 600, it pushed out 103.5 whp @ 13,000 and 44.7 ft/lb @ 10,000. So, my bike in stock form indeed has more horsepower than my 7A-FE in stock form like said before. Nobody talked about gearing, weight, powerband etc. And how in the earth a 4A-FE pushes more than the 7A-FE? Numbers don't lie.

[Blakout16]

well, i do have to agree that my 4afe is much more fun than my old 7afe i have givin' a go at my friend 97 celi st not too long ago and let me tell you, i blew him out of the water

This post has been edited by Blakout16: Feb 5, 2007 - 8:15 PM

[hatchy_gt-s]

the 86kw is probably at the crank, so 76 to the wheels isnt too bad. thats about 100whp and 108 lb/ft.

thats actually pretty good for a stock 7afe! advance your timing a few degrees to see if that'll bring your torque curve to peak a little lower again, or you can build up and raise compression some for more power across the powerband, however i dont think the price of the work would equal the gains. the timing advance is free, just run a higher octane fuel.

that 86 is at the wheels not crank because the spec.s for the torque is 149 @ 2300 an hes gettin 147 an to everyone that is car people haveing everything on the engine creats more Nm

[alltracman78]

His 147 is N/M, NOT lb/ft....
Take that into consideration....

And where are you getting 149 lb/ft?
Or am I interpreting it wrong?