Loss of power in Top End

[guitaraholic]

I recently built up my 4g63 N/T (93 Talon ES) with a few modifications, but my question is. The car has noticably more power then stock, however it seems to peter out at around 6300 rpm, will any of these mods cause it to suffer from top end, also, It was suggested to me, by an engine tuner, that the 240cc injectors might not be able to handle the extra air flow (need bigger ones?), and/or I might need to get something like a K&N filter to lessen air restriction. I would appreciate any help. Here the the folowing mods

- Hacked Air Can (working on making a CAI)
- Turbo Cams (going to get them reground soon)
- UDP
- Removed the Balance Shafts
- Headers
- Ported and mildly polished head (PITA to DIY!!)
- Shaved head to increase compression ratio
- Weight reduction 100lbs (A/C, Spare, ect)
- Engine Fully Balanced
- Advanced the timing a bit
BTW my 0-60 was 6.7, not too shabby, but the power loss at top end concerns me a bit

 

[Raph]

wow,nice 0 to 60 with those mods,sorry i cant help u with ur problem(i am assuming u know ur stuff and ur are properly tuned)..but i do have a question..what brand header do u have?

thanks

 

[guitaraholic]

As crazy as it sounds, Just a Pacesetter header, I repainted it with High Temp paint (its been 2 months now driving like a madman, and only a few little rust spots i have to take care of, but nothing major), the crap that came with it just flaked off. Not sure if they help,, but they weigh like 20lbs or so less then the exhaust manifold, and make the car sound kinda mean at around 4k, plus that's about where the power REALLY kicks in,, almost feels like a turbo. Oh, and to let ya know that I am not over inflating the 0-60 time, It was done with a GPS and the timer starts when you start moving, and its so sensitive that if you start to just roll, like letting off the brake, the damn time starts, so, I have no doubts about the accuracy, when I did the time, the GPS was accurate to 18ft, so its not too bad (4 satalites).

IF ANYONE HAS SUGGESTIONS ON MINOR STUFF TO DO BEFORE(going to stroke/bore it to 2.4) I REBUILD IN THE SUMMER For some added performance I would really appreciate it.

 

[andymoraitis]

First of all, you've got a great mods list and you should be commended on such a low 0-60 time. In looking at your setup, I think one hangup may be the lack of a full CAI.

As an example my stock internals 420A would start to lose it at about the same RPM range that you are. Adding it allowed me to shift at closer to 6700. Following the header and cat back install (the cat back is stock size BTW) I can shift at 7K and the car breathes all the way up to that point without strain.

When looking at a problem of this type, try and work from the front and back and then try the middle. The first thing I think of is the CAI. Since I don't have much more information about your cams, I can't determine if those come in at the right rev range. It could also be a matter of shifting the RPM range through cam timing.

Hope that helps and let us know what happens.

 

[Damn 2nd Gear]

the cold air up here in the northwest lets me shift at 6800-7000 with power

 

[ATOMIK_82]

If you haven't already, try port-matching your manifold & header to the head, this will eliminate "Powerless" turbulent flow and let you scream well passed redline. This is good for a pony or two@high RPM, improved low-end torque and a more linear power-band. And speaking of turbulant flow, get your Intake manifold Extrude-honed. This will remove all imperfections in the plenum and the runners for a "smooth-as-silk" flow from the Throttle-body to the head. As for the injectors, if you plan on more "air intake" mods, upgrade to a 270cc/24lbs/hr. Your stock ECU can still control them from going too rich. So, if you have the money, why not.

Keep tuning! and keep me posted.

 

[DSMguy023]

Hey whats up guys.I have a 90 laser nt w/ the 4g63 motor. i have a k&n hacked air can and gutted cat and exhaust. would the stock turbo cams help me out any? and is there any ecu mods for this car? thanks

 

[DSMguy023]

Does any one know if the nt dsms came w/ an eprom ecu?

 

[mckooter]

wow, the last two posts, seemed to fit so well in this thread

 

[Daedalus]

I doubt that you would be running out of fuel, or that you are leaning out your engine. Your stock ECU can handle up to 400cc injectors but I dont think you need to upgrade just yet. (You could but dont need to, and wouldnt help that much without fuel managment of some sort)

The loss of power you feel is something i had felt on my car. I'm gonna just throw out a couple possobilities...

-Spark plugs/wires replaced? It has been known to get rid of that power slug up there...
-Larger grind cams? HKS 264's should give a bigger top end pull all the way to redline..
-Fuel Injector cleaner? They do get dirty with age, and do decrease engine performance and the amount of fuel being actually put into the engine..

I dont know specifically. I'll let you know how my car pulls in about a week. Its kinda crazy how similar are mod list is.

OH YEA! CONGRATS ON YOUR BUILD UP AND 0-60 TIME!!! VERY IMPRESSIVE!!!
:laugh:

 

[DSMguy023]

i have replaced plugs and wires w/ ngk plugs and wires. a little difference, and cleaned fuel injectors, but no cams yet. i have gotten my 0-60 time down to 6.8 or 6.9. so it helped a little. i can tell a difference in topend power. but it still doesn't want to go past 6grand very easy so i usualy shift at 6-6,5 if i am racing it. but thanks for the tips. and let me know how the cams work out.

 

[Daedalus]

this is just a side thought...

when you tear down your engine to make it a 2.4 stroker... might want to consider a crank scraper... http://www.machv.com/crankscrapers.html

Might as well get all the power out of your all motor.

I also had a question. Do you have a noticable amount of vibration with the balance shaft removal? I am having my balance shaft removed as we speak and was slightly concerned about the level of vibration it might cause. Any additional info you might be able to give me would be great. DId it change the way the engine reved etc? More honda like, and less mitsu truck like?