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92 LX went slower with new exhaust Help,Help

2381 Views 18 Replies 9 Participants Last post by  downsideup09
1992 LX Hatch 110,000 kms 5.0 5 speed loaded no power windows 273 gears bone stock.

The car went 15.1 @96.8 mph bone stock.Timing set at 14.

Then i made up my own ram air with a K&N filter car went 14.90 @ 98.6 mph.

Then i added 355's new posi,Hoosier 27.5x8 tires from a buddy who a stock car he races(free)hooks hard the car went 14.36 @ 100 mph

Then i removed the air conditioning compressor,lines,condesor and the smog pump and front sway bar and the car went 13.99 @ 102.5 mph

Then i put on a set of mac equal length 1 5/8 headers with a BBK 2.5 Inch h-pipe and Dynomax 2.5 inch Ultra flo mufflers dumped at the axle and the car went slower 14.1 @99.2 mph

This was all done with a G tech Pro and on the same road that i always test on (out of town)
What i want know is why would the car go slower with Mac headers and removing the cats and factory mufflers and tail pipes,i should have picked up 20 hp.Is it maybe to lean now.
Any help would be great,i think im going to just put a Zex Nitrous system on it,i still have to put my Kenny Brown subframe connecters on that sitting in my garage collecting dust and i need a shifter.I also just got rid of the clutch fan and put on some electric fans today.

Thanks.....a mid 13 would be nice and a 12.50 on the Nitrous would be great.

Help help help...........
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did you change your timing? You can bump it up some............
The thing i can't get over is i had the 27.5 hoosiers on when i went 13.99 on the g-tech and it felt like it pulled hard i never touched the timing from 14 degres and that was with the stock exhaust.Then i had the h-pipe and mufflers put on and still had the stock headers on and it felt like it pulled hard also,it was not until i put the mac 1 5/8 equals on then it felt slow,like it was just not pulling as hard and sure enough i g-tech it and 14.1 at 99 mph and still feels slow,i just turned the timing down to 12 and it still feels like ****.
I was thinking about putting the stock headers back on or putting the stock tail pipes back on to create more back pressure it's dumped at the axles right now.
Any more ideas guys,im going to be adding a zex nitrous system so should i just leave these mac headers on?Any of you guys use the zex system or should i get the nos system
Thanks for all the help.






08-06-2005 09:53 PM
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The stock headers are probably the best match for that combo. Use a 2.5" catback if you can.
92lxcan said:
What i want know is why would the car go slower with Mac headers and removing the cats and factory mufflers and tail pipes,i should have picked up 20 hp.Is it maybe to lean now.

Any help would be great,i think im going to just put a Zex Nitrous system on it.

Thanks.....a mid 13 would be nice and a 12.50 on the Nitrous would be great.
20 hp from a H pipe and mufflers? That would be nice but it is more like 10-15hp with headers also upgraded.

12.5 requires about 350 rwhp which you are definately not close to, only slightly more than stock, which is about 200 rwhp. You would need a much better set of heads and much better flowing intake to break into low 13's and high 12's. Dont put that nitrous system on without upgrading your injectors and fuel pump or you will definately run into bigger problems.

Adding that offroad H pipe and mufflers would more than likely make it more rich than lean.

Have you pulled the codes to see the computer is seeing?
The Zex system says you don't have to upgrade the fuel system or injectors,can you elaborate a little.What size injectors which fuel pump what is it set at for psi.
Welded my subframe connecters on today.Another quick question, i have a stock cap rotor plug wires and asf 42 c stock plugs in there right now,i was thinking of upgrading a little not a new distributer but what cap rotor plug wires coil and do you suggest.My stock plug wires burnt at the header the first day i put the mac headers on, what plug wires will stand up to the heat on the back two cylinders on the passenger side.I was thinking MSD cap & rotor and some 300 plus wires with a blaster coil,not to sure on the plugs i here the Motorcraft stock plugs are ok.What gap?
Sorry for all the questions.
Thanks for the help GhostDog....



GhostDog 5.0 said:
20 hp from a H pipe and mufflers? That would be nice but it is more like 10-15hp with headers also upgraded.

12.5 requires about 350 rwhp which you are definately not close to, only slightly more than stock, which is about 200 rwhp. You would need a much better set of heads and much better flowing intake to break into low 13's and high 12's. Dont put that nitrous system on without upgrading your injectors and fuel pump or you will definately run into bigger problems.

Adding that offroad H pipe and mufflers would more than likely make it more rich than lean.

Have you pulled the codes to see the computer is seeing?
I'm running the Zex setup and I have 24lb injectors and a 190 lph pump...when i have the car tuned on the dyno with this setup I was told no matter what it says.,...best to go with more fuel no matter what...I spray a 75 shot (small by average standards)...
i run a 150 shot with stock injectors and a 255lph pump..... with timing set at 8 degrees :D im am using the Compucar kit
What kind of ET & Mph do you guys get with a 75 & 150 shot?.

I just bought a Zex system last night and a 190 fuel pump also.
Thanks......
havnt been back to the track for a while and since i have put the nitrous on.....to busy building other car and working some overtime
I am runnig in the low 12's...I was at a consistant 12.8 before then dropped to about 12.3 to 12.4...Keep in mind though that I run on drag radials. I also swapped out my Ford Racing lower control arms for some HPM megabite jr. control arms and boy what a difference!

I don't spray everytime I run...I save it for cars that I think I need it for. I chose to run only a small shot because it is easier on the car and because if you bump into the 11's then you have to put a roll cage in the car to run at track per nhra. I also only spray at wide open throttle in 3rd gear I 'm sure I could do better if I sprayed through 2nd and 3rd but again, it's easier on the car.

I am waiting to see what I can run when the weather cools off. Right now we are running about 95 to 100 degrees down here.
back pressure might be a problem with out the tail pipes on and what was the humidity level when you hit the 13.9 compared to the 14.1 and was the 13.9 at the track and 14.1 on the street. i think you can lauch i little better at the track do to the hot rubber on the ground. does any1 2nd that?
My experience you can always launch better at the track do to all the rubber on the ground and track prepping. As far as weather, I try not to go much in the heat of the summer because it so darn hot and down here we have such high humidity. To get the best times I wait till November when it is about 65 or so and not so humid. Weather plays a big part..also what is the altitude where you are?
i agree completely
What was the weather, temp, between the 13.99 and the 14.1 run?
The weather was really close to same temp & humidity.

I have now got my subframe connectors on and some electric fans.
I also put on a set Weld Wheel Draglites 15x8 with 275/50/15 BFG Drag radials on the back & 205's 15x6 on the front(looks good)

I pick up my Pro 5.0 shifter next week along with my Ford Racing 9mm wires Cap & Rotor with MSD blaster coil and a 190 lph Holley fuel pump.I also got a 82015 Zex Nitrous system off e-bay for $200.00 bucks.

I hope all this crap i bought will help,i guess it doesn't hurt upgrading the Ignition & fuel system a little.I have asf 42c's Motorcraft plugs in there right now,what do you guys think about the Motorcraft plugs should i switch to Autolites when i upgrade the Ignition? 25's on the motor and 24's for the Nitrous?
I wonder if this factory clutch will take it,i beat up on a SRT4 last night that runs 13.89's it had a blow off and the whole bit.:grinroll:
Thanks For the feed back guys,i'll get some pics up of the car this weekend.
Also our local track which is IHRA Now will be opening Sept long weekend for the first time this year,i will post my results.
Thanks..
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Our local track finally opened for the first time this year.The traction was not very good at the start of the day.My first pass i was spinning through first and 2nd 14.07 @ 97 mph 60ft was 2.1.On my 2nd pass the traction was a little better 13.80 @ 98 mph 60ft 1.94.Then i warmed up the bottle and on my third pass i left at idle and then floored it when i got out 10-15ft i ran a 12.59 @ 109.78 mph 60ft was 1.94.My final pass of the day i left at 2000 rpms spinning the BFG drag radials in first and still managed a 12.52 @ 109.8 mph 60 ft was a little better 1.88.I think i need a pair of et streets.We also had a really strong head wind 30-50 kms/hr.I also felt the clutch slip on one of my dry hops.
The car ran good for the first time out,i think she has a little more in her.The motor is all stock,maybe it's time for a upper and lower intake and throttle body or maybe a new cam.
I had the timing set at 9 deg and Auto lite 24's with the 125 shot with some 110 fuel in the tank mixed with premium pump gas.I also got my HPM lower control arms on and boxed the stock uppers.
I guess now it's time for a Motorsport clutch and some et streets so i can leave at 5000 rpms and then maybe with some cooler weather and no wind i will see 12.30 or 12.20.

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haha g-tech... never trust that
those are some pretty unbeleiveable times for simple bolt ons and no h/c/i
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