HELP: 3grand I/C exh.+ car is slower!

[Guest jjohart]

I hope this is just a case of using a "tubes" fabricator to put on bits and pieces without having the tuner knowledge to set it straight, but I just paid 3 grand for my 83 280ZXT's custom I/C (NPR) and 3" exhaust all around (Magnaflow), and I swear the car is slower, heavier feeling off boost, and into boost it seems almost to fall off (I swear I am looking at the stock boost gauge falling off once above 5psi even as I continually apply gas).

My first suspicion was the blow off valve connections..he used a flexible hose to go from the BOV to the turbo, and it seemed to be folding down on the airway in its turning (like the Greek Omega symbol). I was surprised he didn't use a pipe, like other posts on the list have documented.

I did buy some clamps to try to keep the hose rounded and opened at the pinch point, but the vacuum hosing isn't attached (I bought the clamps and hoses at Auto Palace, but haven't gotten to put em on in the dark!).

I am still surprised that there seems to be no quicker spool up to the turbo boost range (e.g 3 on the tach), and again, I get the feeling the turbo kicks in but then recedes in pressure as the boost goes on. I also screwed on the "pop off valve" (supposedly for 15psi-bought off ebay), no difference there either.

I know I'm over my head, but I don't understand what to do. Is it the tech I see a week from Sat to put on a boost gauge and Greddy Profec B that will sort out all these symptoms, or is there something I need to go back to the welder/installer about? The exhaust seems tight and the I/C tubing looks good, but then I don't know what else could have caused this downward performance...it's very discouraging! Is it simply all the goods tacked on make no difference, or even detract, until they're in with the boost controller...I thought the modded pop up valve would be enough!

What could be making the car feel heavier and rev up slower even before the turbo kicks in?

[mobythevan]

You need a boost controller to control the wastgate opening. Just modding the pop off valve will allow you to run more boost, but now you need a way to control the wastegate to get it accomplished.

[Guest jjohart]

YES BUT....why would the car now be slower from start to boost zone with a 3 inch exhaust, and why is the boost actually tapering off a bit instead of rising progressively even within its "restricted"/aka OEM settings?!

I can't believe an intercooler and BOV, unattached to a wastegate boost controller can subtract the gains of a 3" exhaust, can it? Can it mitigate the turbo in stock settings from performing as well as before they were added? I haven't seen that entry in custom I/C and exhaust simultaneous installation results...why me?!!?

John

[mobythevan]

When you install an IC it is going to restrict the air flow by some amount. That will cause lower pressure after the IC. You boost gauge likely reads from the intake manifold(after the IC), but the turbo wastegate gets its signal from before the IC(the compressor housing) if that part of your setup is still stock. So installing an IC and not changing the wastegate signal will result in lower boost in the intake manifold. The amount of drop would be affected by the quality of IC. Better IC, less drop. Somebody else chime in if I am off base here.

[yo2001]

You can't really go by the butt dyno. You might not feeling fast because it's not a "bam!" instant boost like how it was with J-pipe with no IC.

[PETEW]

It's really hard to say if your putting more power to the ground or not unless you did a dyno run before and after. You should loosse some boost to the NPR intercooler but you should be making more horsepower due to the cooler denser air. Did you really pay $3K for exhaust and intercooler piping. Or was the cost of the motor included, or.......? That sounds like a lot of money. I would think the power delivery would be smoother but you should be making more power at the same boost setting. Take some pics so we can see what your working with.

[Guest jjohart]

Sorry if I'm starting a rant, but the previous respondent has stated things seemed to cost a lot...I dunno, I was told speed costs, and I suspect some of the most dedicated and intelligent replies come from people who, out of respect for their do it themselves cost mentality, may be somewhat surprised what a recent Boston area design/install from a well known, reputable but not rip off artiste shop, Will at Custom Tubes:

INVOICE as follows (somewhat compacted/edited for bandwidth!):

 

1.INTERCOOLER (plumbing and fabrication)

Items ordered: 3 in aluminum (2) $75

(8) 2 1/2 aluminium bends $240

(4) rubber connectors $50

(2 ft) vacuum hose 5

(4) hose clamps 8

Square stock 10

Tube for radiator/blow off 10

Bracket for canister

 

IN HOUSE STOCK USED TOTAL+ $421 plus tax

 

Remove fan a/c

remove air filter box

Design and fab brackets/I/C tubes

Fab bracket for canister

cut upper radiator hose trim shroud

cut holes in core support for tubes

fab air filter tube 3 in fab blow off flange

out of aluminium.

Remove turbo inlet hose

Cut hole

Fab spout for blow off valve.

 

Labor=24.50 HRS=1592.50 (& 421.00 plus tax)=$2013.50

 

 

EXHAUST:

 

Muffler S.S $245.00

Cat $145.00

Air filter $70.00

3 in clamp $ 7.50

2 X 3 in 2 hole flange $20.00

3 in stock aluminized $60.00

 

TTL PARTS= $552.50

TTL LABOR+ $390.00

TTL=$942.50

 

I hope none of you view this as bragging rights, except in pride for your own resourcefulness to do the above work at whatever fraction of the cost I paid to have someone else do it. I'm not sure that such self-made technically independent people really have a fix on how goddamn expensive this work is, and I suspect I could have spent a lot more with the few "Z aftermarket seller/installers", wherever they are in the US.

If anyone can cooly remark on whether I've been gyped, that might be helpful, but not just blind "he overpaid" remarks. I am really only concerned as to why, after all this work, even for lack of a boost controller installed yet, my car is slower!!! That really gets ME!

Thanks

John

P.S., is anyone willing to take my photos up to show pics of the work done, as I haven't spent money on an image hosting service (of yet!).

John-83 280ZXT 5 spd

[ZR8ED]

As mentioned above. if the wastegate has not been modded ie where you running stock boost before?.. if so, then the extra length of the i/c pipes and the pressure loss of the i/c would give you the feeling of a slugish turbo... even more so if your i/c pipes are not as short and efficiently laid out.

 

If your i/c pipeing is larger than stock, then you have even more air to compress before the throttleplate before the boost can rise..hence more turbo lag.

 

I don't think the 3" exhaust is going to be noticeably benificial when you have actually slowed the response of the engine from the intake....(i/c and pipes)

 

When you start to turn the boost up, THEN you will see the changes.... you may still find a slightly slower response from the turbo, due to the same issues (longer pipes and i/c to pressurize)...BUT then it should come on like a freight train.

 

Have some patience, and wait till you can crank up the boost some...

BTW also mentioned above, WHERE you measure the boost pressure is important to consider.. the acuater gets its signal from just the other side of the turbo housing... your guage most likely reads from the manifold...those two signals are now going to be reading much differently from now on.... the manifold will ALWAYS read a lower boost level than your wastegate actuator (assuming the stock actuator getting a signal from the stock location on the turbo....)

 

Good luck!

[SleeperZ]

Considering all the labor involved and the quality of your parts, I think you did ok money-wise.

 

You need to check for leaks in the intake, especially your "BOV". If that is set soft, it will leak, and you won't build much boost, and it wil taper off like you describe. A bad pop-off would do the same thing, but you'd hear it, and 5 psi would be too low for it to release on you. Just because the return to the turbo intake is flexible from the bypass valve, it will not cause a lack of power.

 

Mobythevan is right on in his assessment of the boost drop as well. The IC will restrict the airflow slightly, and if you are still controlling boost off the compressor housing, your manifold pressure will drop.

[Guest jjohart]

Ok on checking BOV etc, that'll have to wait until my Z tech looks at it in 10 days . I still wonder if the 3 in exhaust set up was more than a whim of difference, as I did when I put a Flowmaster on a 2 ton Chevy camper a couple of years ago...that had little effect on power or economy.

I understand that a turbo car doesn't gain lag offline from lack of backpressure in a larger exhaust, but really...shouldn't I at least be noticing a little more oomph/not less in moving up to the turbo boost area of power?!! I mean, I put a 21lb "slightly" lightened flywheel on with a hybrid clutch about 3 weeks ago and I definitely felt that difference (while some discerning members on this site were egging on about their oh so superior 11lb alum. flywheels). I'm sure there was no weight loss in moving to 3", and in fact it is probably a bit heavier (Magnaflow is no butterfly), but apart from a vaguely Corvette like burble at idle (and a bit more drone in throttle on/off "light" application), I can't tell the@#$% difference from the stock. Is there a "yet" in my intake looseness possible problem that would be holding exhaust back? Is it possible I EXPECT too much, that I shoulda looked at the 20bhp as not seat of pants detectable, more of a macho badge of membership with the know alls? I dunno, but I am really feeling stupid about all I've learned about Z's on this list..if anything! Honestly, my goals were having a limited lag GT, not a race Goat/Corvette killer, but I sure as hell as hope a good shot of boost once the car is checked and boost controller installed is like a fresh breath of Nitrous compared to where the car is right now! Three grand, my 5 year old should shoot me!

John

[Guest ZmeFly]

You now have an IC, your turbo has to charge the pipes and the ic, so effectively at the intake manifold you are no longer getting 7psi of boost, depending on the pressure drop you may only be getting 5psi of boost for example.

 

So it will be slower to build boost. Just get yourself a MBC and then you will say HOLY SHYTE BATMAN, and notice what that turbo of yours is really about.

[PETEW]

WOW, I never knew it would add up like that. Sorry if I sounded like a smart ass but that just sounded like so much money. Stinking labor is ridiculous. I'm not sure anyone can give you an honest assesment without seeing what was done, and feel what it runs like. Can you take the car back to the shop that did all the work? I would think after investing the three g's that they would be willing to give you a hand. It sounds like you have a leak somewhere. It's amazing how a small leak can cause major problems. With the mods that you have done you should not feel like the car has less power. Start looking for leaks and go from there. Sorry I can't help more.

[Guest Cusp]

John, don't over-react. You've done the hard part, and that's stopped talking about turbo/intercooler/exhaust upgrades and started doing them. Nobody here is going to tell you this should work A-ok first try. There are bugs to work out, and tuning to be done, rest assured.

 

As for the money, it only seems to us you spent a bit much because we approach the project much more methodically than a mechanic. He did start to finish, 24.5 hours labor. Me, personally, I bought my turbo 3 years ago, the NPR about 2, my P90 head a little while after that, got my BOV this summer, see where I'm goin with this? You know how many times I went back to ScottyGNZ's NPR install page? I haven't even done my project yet but I've done it about 50 times in my head, and about 5 or 6 times to my wallet. You did not overspend if you did none of the work or prep. Pipes cost a bit much though, for being in stock....

 

Anyway, I agree with the previous posters about the IC reducing your intake charge. Think how much more volume you've added between the turbo and the intake manifold. All that tubing and the entire IC need to fill with air before your going to be +psi , and your previous setting of 7psi will only get you 5 or so now, even though your guage says 7.

 

Here's a quick fix that may make you feel better, and it's how alot of guys prefer their setup anyhow. Go buy a few feet of fuel injection hose or any not flimsy ass hose will do. Look down on your turbo, and find the hose going from the wastegate to the compressor side, or the aluminum side where air leaves the turbo. Here, I'll even take pics cuz I like ya.

 

Now put that long piece of hose from the wastegate to your intake manifold directly. That will give you a true 7psi, provided thats what your wastegate was set to before.

 

edit: This is a T3/4 but yours is similar. Don't worry if it looks a bit different, mechanically it's the same.

 

Good Luck

[Drax240z]

OK, I have to comment on the labour to fabricate intercooler piping.

 

First off, I haven't seen any pictures of the quality of work, or the finish, I would expect it is top notch.

 

I've done intercooler piping now for quite a few cars. The last customer I did some for was an SR20DET conversion, using a starion intercooler. I charged him for 6 hours labour. It took me closer to 12 but I was cutting the kid a break, and also undercharging because I didn't have all the tools necessary to do the job quickly. (for instance, I was cutting piping with a hacksaw, rather than a bandsaw which would have saved quite a bit of time) In my opinion 10 hours is about right and will be what I would charge again for doing this.

 

However, now it gets interesting. If he wanted all the welds ground smooth, and the pipes polished within an inch of their life, then I can see another 8-10 hours in labour to take it that far. The finished result should be seamless, perfect and polished, but I could concievably charge someone 20 hours to do their intercooler piping if it was done to that level.

 

So I think that is a reasonable amount to pay for some quality pipes. It seems these guys have explained why the car feels slower sufficiently.

[Z-Gad]

Keep your chin up, You've done the hard part. The rest is gravy and don't worry, you will feel the difference. If you have time and feel a little adventurous, you could do what was just suggested and run a hose from the intake manifold to the wastegate to sense boost. I guarantee you will notice a difference.

[fl327]

ditto what zgad said.

run the wastegate line to the intake direct, that will bring boost back up to where it was before, difference now is that you are intercooled and it will be faster.

[Jersey]

Hey John. Sorry your having a bad experience after spending that kind of cash. Dont worry, your 5 year old son will value greatly from the experience and knowledge you can hand down to him about this. That's how i justify it when spending extra $ on my Z... my 4 yr old son wil LOVE it! lol. Everyone has great suggestions and i'm sure you'll get it squared away.

 

The 3" exhaust shouldn't be causing any of your issues - i ran the same and have no bad side effects swapping from 2.5".

 

Me, i would #@$%can the POV. Plug it. You have a gauge, right? Keep an eye on it and you'll know when somethings wrong, just take your foot off the firewall! After you get used to how the Z reacts in all different situations, you wont have to stare at the gauge everytime you're on it hard, you'll be able to feel if she's right.

 

I would also take the "blow off" hose off of your BOV (i think you said it was recirculated in between the AFM and T, right?) and try driving it around like that for a test to see if it leaks. I used to have mine (1g DSM BOV) plummed to recirculate but disconnected it one day just to hear the "WOOOSH" and haven't hooked it back up since (Yes, my Z runs fine with it venting to atmosphere for some reason) But the reason i mention this for you to possibly try is because i found out that i lift my foot a bit too fast off the pedal and she vents a little, then if i get back on the throttle a certain amount, i can hear it still blowing off, but just sometimes. If i lay my foot into her, she seems to seal but more often then wanted, i can hear it not sealing. I would have never known this with it recirculated because you just cant hear it. This winter i need to actually spend $ on a real one (my son will lOVE it ) but, good thing i wanted to hear the bling "woosh" because i probably could have overspun my stock T3, just by having it throwing air around in the engine bay instead of my intake. Just a suggestion as a test.

 

When i installed the NPR IC, i did feel like it gave me a little more lag. It seemed to moved the hit up about 300rpm. On the other side of the coin, i cranked the boost up a bit and when she hits, it's awesome

 

Anyway, I'm rambling but i just wanted to see if i could help in any way with the experiences i've had. If you're ever down around the area (NJ), stop by. I'm no expert but i'd take a look at it for ya. 3K is a lot of coin to spend to not have you pinned to the seat with a nice big grin! Let us know how you make out. Good luck.

[fl327]

open vent bov may not be the best way to keep turbos alive, but theres nothing like the looks on peoples faces when a 70s car hits WHOOSH on em!! the dsmIg works for you w/o the hose attached? thats cool, i know 1g owners who take the hose off and that sucker is pretty loud, it will be easy as pie to get a aftermarket bov for you since they make bovs with flanges that bolt right up. With the open vent, I notice no lag between shifts. IME experience, the only thing that made boost response bad was initial intercooler fitment, I still miss the KABASH feeling of boost when the jpipe hits, even though im faster with more boost and IC.

[yo2001]

This might be helpful to all you DSM BOV user. This will make th eBOV as good as Greddy type-S

 

http://www.thedodgegarage.com/turbo_bov_mod.html

[Guest szlash280z]

my 3" exhaust slowed my car down too while running it at stock boost. I was running with just a downpipe before though.