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Discussion Starter #1
i went up to the races this weekend in ind. one of my buds is a student at L tec and they have alot of fun in the drag program they have there on the weekends. well when i got there they really liked my car and next thing i knew i was in the line on the 1/4mile drag(they talked me into it) they all were expecting a 13 second 1/4 but i was the olny one there that knew that my car was about stock!! after i went they gave me the time slip i was very happy with it but they wernt. i got a 15.3 at 91.2 mph and all i got done is intake and exhaust-headers arnt on yet and it was on a empty tank and about 80pounds lighter than stock. is this good for what is done. i think it is but please tell me
 

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Discussion Starter #2
i was drivin a 83 280zx
 

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Sounds very good to me and maybe almost too good. Lets just say stock times for the 280zx are supposed to be in the mid to high 16 range so running a low 15 with just intake seems too good to be true. This is even better than Tony D's 280z that runs a 15.3 becuase his car has a k&n drop in filter, exhuast, 3.9 gears, and 60mm tb. Personaly I would say you have more than just intake done to your car but that is just me. Stanger things have been known to happen than a stock car running faster than it should. Another thing to keep in mind is that most modded 70-83 Z's with similar mods to what I have only run high 14's to low 15's so again doing this in a stock car means you must be one **** of a driver. Out of curiosity what were you launching at, what was your launch technique, and what were your shift points? Good job.
 

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Hey Zman14.2, are you from Indy? Where about?

Dave
 

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Discussion Starter #6
i live down in springfield IL i wish i lived in indy and i was kinda putting in less than there was it has intake, exhaust, short t shifter, and a new clutch, 60s tires/new. droped clutch about 2800 rpm. that was one of the best runs ive ever done i know for a fact but now that i have raced on a track i really like it i always raced one the streets with people who thought there cars were alot faster than they really are. my car pulls hard till about 5500 rpm and that is were i always shift.
 

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Discussion Starter #7
sitting in my garage i have performance headers and a turbo afm soon i will be buying a tb and spacer so i can put it all on at the same time. next summer i plan to go back and hopefully hit 100mph 1/4s.

i know putting on a larger tb doesnt do much but would it be more noticeable if i did the afm with it

all my buddys race around in their fox body mustangs and i can beat them till we hit 60 mph then they walk all over me after that i was wonderin would a 35-45 hp shot of nos hurt my car at all it i were to use a dry system. i dont want to hurt my car i just want to kill my buddys 5.0 in the 1/4 i dont care what happens after that. how much would a small shot like that take of 1/4 times like .3 or.4 sec
 

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Well as you have probably read on this site the larger tb and afm do nothing for performance. There is some debate between steve280 and I on if tuning using a stand alone fuel system can help make more power from the larger tb and afm. With both agree that with the stock efi that the larger tb and afm do nothing to make more hp or to get better 1/4 mile results. What I've always read is that the head is the main restriction with the intake manfold being next so by opening up the tb and afm it will still bottle neck at the intake manifold and head. I believe Tony D stated that the stock tb is good for up to 230hp and 7000rpm worth of breathing. Still steve280 believes that the stock efi is one of the major bottle necks of the 280z and that with the tuning capabilities of the stand alone system gains can be had from the larger tb and afm. Still no proof has been provided to show hp gains or lack there of and same goes with 1/4 mile times. I do know that a guy on here, Yo2001, did the larger afm and noticed no better 1/4 mile times at the track. I also know that on the 84-89 300zx the larger tb used to be a popular "cheap" mod to do like it is here until someone finally dyno tested and tracked tested it on both his non turbo 300zx and turbo 300zx. Both tests for both cars came back stating that it showed no improvement. Still some argue that the 300zx VG engine is different so it sheds no light towards what it would do for the L28. People, like TonyD, have used math and physics to show that the stock tb set up is fine as I pointed out above for over 200hp and over 6k rpms. Still some people claim that the car feels much faster after doing the swap. Then it comes back that the "feel" is due to better acceleration at partial throttle but that at wide open throttle flow is still the same as with the stock. I could go on and on but the point is that it's a debate that will continue until someone does some tests to prove something. From what I've read over the years from people here I would almost gaurantee that on a car like yours you would see no gain and that doing it would be a waste of money. I would only consider it if 1. you had a port and polished head and/or 2. you had a stand alone fuel system. As for NOS I won't touch it but again thats another heated argument. Besides the potential damage to the engine I just think it's cheap to use NOS. What happens when it runs out? You are no longer as fast. I like engines that will run just as fast the last time down the track as it did the first time down the track. It's a personal choice. Almost any car can be fast with NOS but not any car can be fast without it. Good luck and good runs
 

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A stand alone fuel system doesn't use an AFM. :)

And I don't think the 50mm TB is good for 6000+ RPM's or 200HP on a 2.8L engine. Then again the stock EFI manifold isn't good for 6000+ RPM 200HP either. I think a 60mm TB and turbo AFM helps power from 5000-6000 but like you said, it's a lot of work for small gains and with most people's crappy tuning, they probably end up hurting power lower in the rev range so the time slips are the same. I also had to use turbo sized injectors with the larger TB once I changed to SDS as I could see I was at 100% duty cycle trying to fuel the engine at WOT. This could be the problem some people have with the larger TB and AFM, the injectors can't keep up? I do agree it isn't a night and day difference.

What I do know for sure is the EFI manifold is a major problem to making any sort of top end power with these cars. I had a well ported N42 intake, 60mm TB on the engine in my sig and it ran -pretty- strong up to 5500-6000. I kept trying different tuning and adding performce parts to the engine, changed the head etc but they didn't add as much power as I thought they should. I can see now the EFI intake manifold was the problem.

Given the camshaft I ended uop with didn't really start working till 4000, the car wasn't that quick with all the mods I did before the last one, which was the sunbelt designed intake manifold. When I replaced the intake (same size 60mm TB), I had to richen the EFI 20% from 4500 up to keep the fuel mixture the same as before and the car now pulls like a rocket from 4000-7000 with no other change. I just "thought" it was making power at 5500 RPM before!

I've also noticed that an L28 with SU's runs MUCH stronger than one with stock EFI (larger manifold runners, 2 big "throttle bodies" etc) so if I was the zman 14.2 and wanted some "easy" power, I'd install a pair of SU carbs when I had the manifold off doing the header. I can promise him THAT will wake it up! Plus the whole SU setup will be about what the 60mm TB costs.

This is my earier setup with the 60MM TB

<http://atlantaracing.tripod.com/280zmods/ZEngine.html>

This is the latest one that works.

<http://atlantaracing.tripod.com/280zmods/myzengine.html>



Post Edited (Oct 11, 11:44pm)
 

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Good point steve. Yeah I forgot to mention that the stand alone fuel system doesn't use the afm. Anyway zman14.2, you can see how much is involved with making these engines perform and how many different view points there are to making them perform. Like I said and like steve said the stock efi just won't let you take advantage of the larger tb so I would hold off spending the money on it. My best advice is to use the search feature for discussions on the tb set up and see where people experienced in engine build ups, like steve is, stand on the issue. Then after reading what people have to say decide for yourself what you are going to do. I will tell you that with my set up, look in sig, that I will not be doing the 60mm tb becuase I doubt it will do anything for my set up as the stock efi is already running at almost full capacity with just the few mods I have. Hopefully between steve and I you can get an idea of what you want to do. Good luck.

Hey steve, want to come to CA to install an SDS system on my Z?LOL
 

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excellent posts, i wish these forums could utilise the "sticky" system.

Mat
 

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Discussion Starter #12
thanks for all the advice guys were do u guys get your fuel systems at
 

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The bitch with these cars is it's a "make your own" or settle for SU's if you want something better than the stock EFI.
 
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