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My new 97 z28..time to mod. Need some help

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My new 97 z28..time to mod. Need some help

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Old 10-07-2018, 07:31 AM
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My new 97 z28..time to mod. Need some help

The car is a 97 z28 a4
I bought an aluminum elbow that came with an airfoil and the eBay intake.the eBay intake gets a bad rep because the elbow is all round and doesn't transition to oval for the throttle body,hense why I bought an elbow too. I will be combing them for a very very nice intake and will heat wrap it and it runs into the bumper.
1...what I'm wondering is since the elbow doesn't have a vent port for my opti spark would it be better for me to make the be t in the intake tube be for or after the maf??? Stock its behind but then it can't correctly meter that incoming air rite ? So would it be better if I vent it be for the mafs?
2....if I install longtubes and delete the egr and air pump and cap everything off, will I have driveability issues ?? Cel I don't care but will it idle correctly and go wot properly ? I do plan to tune it but I want to have as many mods n bolt ons as I can be for that so don't have to return. I do plan on heads and cam too but those will be my last 2 mods as that's when I want to tune.
my only mods so far are muffler delete,throttle body coolant bypass and composite maf ends. I'm pretty sure the rear end has gears unsure of what ones but stock tires my Speedo is off by 10 at 55 and its rpms seem high.
She pulls hard n hauls ***..

Last edited by Marshmaro; 10-07-2018 at 07:47 AM.
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Old 10-07-2018, 09:46 AM
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Re: My new 97 z28..time to mod. Need some help

1. The vent for the Opti vent goes AFTER the MAF. You have the air flow concept backwards. The air gets measured as it flows through the MAF sensor, and then flows OUT of the elbow towards the Opti. It moves in that direction because the vacuum line from the intake manifold to the Opti is pulling in toward and into the intake manifold. Since that air ends up in the combustion process, it has to be measured by the MAF sensor, so the PCM can set the injector pulse to supply the correct amount of fuel.

2. Deleting AIR will not affect drivability. The AIR pump only runs for a couple minutes on startup, to burn the excess fuel from the rich cold start mixture in the exhaust system, which generates heat to help the cat(s) getup to operating temp faster. Cats don’t start to work until they reach ~600°F. Are you keeping the cats with long tubes?

Deleting EGR will increase emissions of NOx. Does not affect performance, whether you keep it or delete it. Do you have a tailpipe emissions check? EGR is not used at idle, not used above 3,500 RPM, not used at WOT. A minor benefit of EGR is reduction of detonation (knock) under certain conditions like lugging the engine at low RPM in the wrong gear - not something knowledgeable performance guys would do. For normal driving, the PCM does make some minor ignition timing tweaks based on EGR usage, but nothing you would notice.

Both deletions will set codes/SES light, as will deleting the cats. Very easy to “tune out” of the PCM. The constant SES light will mask other problems/codes that may turn on the SES light, some of which could even relate to engine damage. Why stare at a constant light? While it will definitely be less expensive/more convenient to have all the mods in place before a tune, most of the mail order tuners can do the basics like tune out the codes/SES light, and can even pick up a quick 10-15HP by leaning out the overly rich stock program target A/F ratio, used at WOT. Once you've had a tune, they will generally update at a lower cost. Even if you are ultimately looking at a dyno tune, getting rid of the codes and picking up the HP would seem like a good idea. Minor problem is finding a good mail order tuner, because not many want to work on the LT1 any more, but there are a couple that can do the basics outlined above.

Mail order tuner could also correct the speedo for the new gear ratio. Right now, the MPH vs RPM mismatch could be screwing up the A4 shift points.

As far as transitioning a round pipe to fit the oval throttle body, there is $6 Fernco sewer pipe connector that works well and looks good. I’ll post a pic when I get back o my PC.



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Old 10-07-2018, 10:17 AM
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Re: My new 97 z28..time to mod. Need some help

The 3" Fernco 1056-33 connector might work, depending how much room you have.


https://www.camaroz28.com/g/picture/11252655

Scroll through my album..... there is another side view. I'm having a problem attaching photos.

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Old 10-07-2018, 10:49 AM
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Re: My new 97 z28..time to mod. Need some help

You must have miss understood .
with the opt vent I mean wouldn't it be better moved forward in front of the mafs as it is where the air meets the elements to be metered . where it sits stock it doesn't get metered ..
I already have the elbow. I'm actually installing that and the airfoil later today then just run to stock bend and cone filter until the eBay intake arrive to replace it and finish the routing ..
I alsoidle at 1000rpm in park and 800 in drive. I feel this is high as I have to press the brakes harder than you need to hold the car at a stop . icheckedfor vac leaks and have none and no cel that would effect that . but my car runs cold,very cold like 170degrees . does this cause the elevated idle as its trying to warm it up to operating temp?
and I plan on getting rid of my cats with the long tubes. No emissions for me !!!!!!
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Old 10-07-2018, 10:54 AM
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Re: My new 97 z28..time to mod. Need some help

Also the eBay full intake was 45$ and the elbow with the airfoil was 55$ so no offense to the other intakes made that are 4x the price. The only benefit I see them having is looks as they fit over the portioning valve cleaner,big deal....I can't imagine them making any more power than my setup..
lol. I've usually used pcv pipeto make and route intake but was too lazy so I ordered them . will combine them. Modify and do my best..pics coming soon.
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Old 10-07-2018, 12:30 PM
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Re: My new 97 z28..time to mod. Need some help

Originally Posted by Marshmaro View Post
You must have miss understood .
with the opt vent I mean wouldn't it be better moved forward in front of the mafs as it is where the air meets the elements to be metered . where it sits stock it doesn't get metered ..
All the air that passes through the MAF has been measured. If you took the Opti air out in front of (before the MAF) it would not be measured. You have to measure it because it ends up in the combustion chamber.

No air enters the stock location from the Opti vent. That is where the air is taken out of the elbow, and flows to the Opti. The air that passes through the MAF divides into three streams:

1 - the air that goes into the intake manifold through the throttle body

2 - the air that leaves the elbow, passes through the Opti and enters the intake manifold through the vacuum connection.

3 - air that leaves the throttle body and goes through the hose to the passenger side valve cover. That air is pulled through the crankcase by vacuum from the PCV valve on the driver side of the intake manifold.

All three streams have been measured by the MAF before they split, and all three streams combine in the intake manifold and get used in the combustion chambers.

I can assure you with 100% confidence that the GM engineers got the Opti vent location right.

http://shbox.com/1/opti_vacuum_harness.jpg

http://shbox.com/1/opti_vacuum_hose.jpg

I already have the elbow. I'm actually installing that and the airfoil later today then just run to stock bend and cone filter until the eBay intake arrive to replace it and finish the routing .
Be careful with the throttle body air foil. Some of them are poorly designed and block the idle air passage in the throttle body. And, there is little if any HP gain from a throttle body air foil. It can cause more problems than it is worth.

Drivetrain Modifications #4

I also idle at 1000rpm in park and 800 in drive. I feel this is high as I have to press the brakes harder than you need to hold the car at a stop . i checked for vac leaks and have none and no cel that would effect that . but my car runs cold,very cold like 170degrees . does this cause the elevated idle as its trying to warm it up to operating temp?
The stock programming for the A4 idle - FULLY WARMED UP - speed is 550 RPM in gear, and 650 RPM in park/neutral. The stock tach generally reads 100 to 200 RPM higher than actual RPM.

Stock programming:
coolant - - in gear - - - neutral
24 degF - 800 RPM - 1000 RPM
46 degF - 800 RPM - 950 RPM
68 degF - 800 RPM - 900 RPM
132 degF - 750 RPM - 850 RPM
154 degF - 650 RPM - 750 RPM
176 degF - 550 RPM - 650 RPM

The dash gauge reads from a 1-wire sensor in the driver side head. The PCM gets the temp from a 2-wire sensor mounted on the water pump housing. No guarantee that both temperatures are accurate or the same. It the gauge is showing 170 degF, the PCM may be getting an even lower temp from the sensor in the water pump, causing a high idle. The only way to know the true engine RPM and the coolant temp being reported to the PCM is to use a real time scanner on the PCM. Is it possible someone has installed a 160 degF thermostat (stock is 180 degF), and reprogrammed the fans to come on at lower temperatures?

If you want more info on scanning the PCM, there is a link to my LT1 scanning guide on the "Computer Diagnostics...." forum:

https://www.camaroz28.com/forums/att...canning-r2.pdf

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Old 10-07-2018, 02:30 PM
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Re: My new 97 z28..time to mod. Need some help

OP...as you install your home made round hole to oval intake (read not something most would do)….make sure however you clamp this so you don't get any vac leaks....which will cause issues.

Might want to spend some $ on a vacuum gauge, FP gauge and OBD2 scan tool. Those will be very helpful in chasing issues very likely to happen on a 20+ year old car you modify

Your higher than normal idle could be a vac leak you have yet to find...again a vac gauge will help diagnose several engine issues...if you know how to read it. You may have no vac leaks but the temp sensor on front of WP "may" be faulty telling PCM the engine temp which could be false.

This site is very helpful and had a chart of resistance values vs temp for this sensor...
4th Gen LT1 F-Body Tech Aids
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Old 10-09-2018, 01:51 PM
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Re: My new 97 z28..time to mod. Need some help

Also be careful with metal intake elbows. Metal is more prone to heat soak than the rubber elbow, so you may actually lose HP from hotter air coming into the engine.
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Old 10-09-2018, 05:43 PM
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Re: My new 97 z28..time to mod. Need some help

No..I am not installing a circle pipe to the throttle body . I have the proper elbow that even came with a nitrous port too.
I found my high idle is caused by my low operating temps . I fought cooling issues when I got the car and finally gave them worked out, lol I guess I better reinstall my thermostat .
I have 0 driveability issues with the airfoil ,elbow and intake..
next I will heat wrap it all and post a pic..
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Old 10-11-2018, 09:34 PM
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Re: My new 97 z28..time to mod. Need some help

I have it installed enough for now and decided what I will do.
I will continue to use the stock bend as its the sane diameter through out but an going to replace the metal pipe coming off it with a .5 in larger plastic pipe and bigger filter still too.
As you see now what I was talking about with my elbow. I don't think I need to heat wrap it at all actually. I ran the car for over an hour then the last 5 min be for I got back I ran it hard and from the filter to the throtllebody was the same temp , well at least to the touch .. So the cai in conjunction with the throttle body coolant mod and plastic ported maf end it runs much much cooler through the whole intake. I don't know how much the airfoil helped but it was an extra 7$ only with the elbow so why not.
so this was for sure a worth while mods.
it also didn't throw any cels at all and the only way it effected driveability was in a good way..pulls harder low end and top end. Kicks down harder , shifts actually seem more firm and it sounds great . I would skip the eBay intake tube as imo its too small. I feel a 4 in coming off the bend into the bumper and a larger filter could perform better and maybe give a louder whoosh . lol its actually very loud. You would think my iac is stuck open or a vacuum leak but its just that loud..I also bought paint match spray paint to touch up the rust from under the stock air box too..
also any opinions on the 5th gen dealer option rims I have ? I had them for sale and threw around the idea of getting the 4th tire and running them . the rears are 275 and fronts 235 both 21inch on Pirelli zr . rears have like 200 miles and the front one us brand new..omg I can't believe the price if the rear tires..geez..I just wonder if they clear everything . my car sits stock.
and to clear up something...I read a lot of back and forth about 5x120mm rims and our cars..they fit perfect . and run perfect . I got my 17s off a g8 .




Last edited by Marshmaro; 10-11-2018 at 09:37 PM.
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Old 10-11-2018, 09:41 PM
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Re: My new 97 z28..time to mod. Need some help

Here is my car with the rims from the g8...I really like its stance and look which is why I haven't decided on the 21s yet.
tires are hankoook 245/50r17s.

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Old 10-11-2018, 11:39 PM
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Re: My new 97 z28..time to mod. Need some help

In the past, some people running BMW 120mm bolt circle wheels on the 4th Gen 120.65mm bolt circle have experienced loose lug nuts and broken studs.
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Old 10-14-2018, 09:23 AM
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Re: My new 97 z28..time to mod. Need some help

Originally Posted by Injuneer View Post
In the past, some people running BMW 120mm bolt circle wheels on the 4th Gen 120.65mm bolt circle have experienced loose lug nuts and broken studs.
I checked my lugs 2x . once after install and some hard cornering ( which I think is this cars weak spot ) and then a few weeks later and didn't loosen at all..I can't see how the rims would cause studs to break . they fit perfect , no wobble or un even pressure on one stud or something .
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Old 10-14-2018, 10:05 AM
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Re: My new 97 z28..time to mod. Need some help

The only way the 120.65mm bolt circle conical lugs will seat into the 120mm bolt circle holes in the wheels is if the studs bend slightly, or the holes in the wheels deform. Works for some people, documented that it doesn’t work for others. As a graduate mechanical engineer/licensed professional engineer, I wouldn’t do it, but that’s just me.
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Old 10-16-2018, 11:13 PM
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Re: My new 97 z28..time to mod. Need some help

Originally Posted by Injuneer View Post
The only way the 120.65mm bolt circle conical lugs will seat into the 120mm bolt circle holes in the wheels is if the studs bend slightly, or the holes in the wheels deform. Works for some people, documented that it doesn’t work for others. As a graduate mechanical engineer/licensed professional engineer, I wouldn’t do it, but that’s just me.
Then mine must have been bent at a prior time..and you don't think maybe the tiny bit of room the lug holes gave may have corrected it ?
lets not get in a **** fit about the rims its off topic . I put them on 0 problems and gave had 0 problems and have raced and daily driven it so I'm sure it will continue to have 0 issues .
I seen a set of no emission long tube headers on Craigslist here for 50$ so I might get them . but Idk id rather spend the dew extra and get mid-lengths and no cats etc because my car during summer is daily driven and mainly by my wife . lol she hated the car so much when I got it but its grown on her now a lot.. Me? Love its power and engine performance but handling and comfort severely lack
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