Back from the dyno and disappointed

[Billy Mild]

After all the rushing around I have done this past week the ZR1 was able to make its appearance to the dyno. Last year I had the car dyno'd and it made the best of 330 WHP. The only mods at the time were Borla Axle back exhaust, center resonator delete, and airlid opened up with KN filter.

This past week I have installed a chip from Haibeck with mods to support the following, SW headers, high flow cats(C6z06), and a new x pipe midway through the exhaust. The car put down 334 WHP as it's best run. To say the least I am very disappointed with all the mods I only gained 4 whp. I will say that it's 90 degrees outside and really humid. The dyno operator told me I am running way too rich. It's in the low 11's for AFR. He said it should be 12.5-12.8 for an NA application. Last year it was cooler outside. The dyno is at the same shop so that can't be any different as far as correction factors go.

Any ideas WTF is going on?http://uploads.tapatalk-cdn.com/20160626/6d6ffdd63fc617e8a3b3fe3173a0b8f5.jpg

Video below: https://youtu.be/bCJuFdR_M2c

[efnfast]

Did Marc know you were doing headers when he did your chip? Running rich will cost you a lot of hp.

[Billy Mild]

Yes I told him about all my mods. He enabled anti backfire mode and extra fueling for the headers.

Sounds like I may need less fuel.

Sent from my Nexus 6 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Billy Mild]

I have attached the dyno runs. The one when I was stock all I had was 3.73 gears and a crappy "tune" and Borla axleback with center resonator delete. The chip looked stock but who knows.

STOCK with center resonator delete and Borla Axleback
https://lh3.googleusercontent.com/wd8QFdpoAszWrBOjPNJZBBY13-QOYV6y5IR5wCjsxbm08qW3beSZU6p2qkm7GAR76Ys9KWjKzjbu FKA8A74dJaJ4TI-EqC8F2Z4srJgZmfuJwc-xaiwZDt0WOgcNQZgkqZt3SEdVbnrTG7o7_83GfEHmnOHK2OzLx 4m1yfByEL3qoCBA63kOkeZD1RTrZl0XZCZ5lJOJtzopG8xfsKO--t8CjebJJeKX0Ke7uNX0PK9TH4z2sU6t0fKE4n8wC9H7AA47xIn Pq6Q6ZVGGiB9LyFYarK9HTlk8SiMpzC3xjgmyx3eqwh44c2SGN f89741s09iRMK85acg1ih8p9QN0ByYAKx-EwC54je2usOjAGDmAlBGjBCVbhmDV7FGjat6vwnDrkruv7VYyn d7yWMAoAa8GKqwQPeOr4Esun11j7n-EFmMyembIiadv0NDhVKk69VA4Or8V0Zhvb50BSzul4WwgETGbj AQadruniAk8vfEF6MDkfJ4WFqbtMNrTqvzay9HbLCjw_PcG5RP a7lnSUdd77xhEfv_yNM9gVfRvD-w7VvT-dwQWO4I0hrQQFQ1VzElM-OkH-TBToZ8ie3L_rd5K4K-NOeg=w618-h799-no

SW Headers, C6Z06 cats, 3" exhaust with x-pipe, Borla Axleback, Haibeck TOON
https://lh3.googleusercontent.com/OHUU2qY21Wcik68_js-XyX8911RZ8skmNXgc_8YrxI1uNZFCxsz5U2ElS5t0w1ws19tI_ V515coyrRR2T6lRJuh_n46TKIJY2j1f9IGbeDmNMxB3ZjGleBl 8FCNt67g_ZdfJ9faGTwg7R0mIklk4Ha6r0moYrEjzp-IS7bfKotToE67EVZiJwymWmVlLOsVBLfpwiR2GYwAqMhwfwSvp odZ7__RZhl0lMhgTFhQy9gyDknku96s7943ZTdWco_odpMHtE0 Vbt-AQSgwGlVE_3iV36sJbmR4n9CnTrqp7bVk7PepJGHE9_DELdehw AgyJLCYxSwJXKJk0Q8Mmh7w396Ry1nXIs-C263Oiyvw5khG_eyuQFgS091UedPXqjGJQGZNYgQ90bcoYmPaw gQ_1_lnye9SSCGkWyV184XnUpV6Zud7Fp_UEpvlhNMepmyLuNN bWATztQYfaG4Eh-vbrRM0Px7anuJuv_Hf5ajMCWZL9HCl2aWsRvMWCY7OvuZjwkuK txwoOyBoQVfjgnQzCCmzQv8-02P73zGjk0jUN-Jz-sPuEx4cO5M0QD_uSzH-7R0lILZxuDULr5r-APTmTpNuFLY5VVdo=w618-h799-no

[efnfast]

Headers, exhaust, retune, took me from 311 to 353 RWHP.
Something is wrong if you only had 4 hp gain

[tpepmeie]

Weather like that can play a big role in the results, despite the correction factors. Hot, sticky air seems to really hurt the performance in these engines. The bad air will also show richer air-fuel ratio than you'd see on a cool, dense day. I'd look for better weather, and try again.

[Billy Mild]

That is exactly why I made this post. I have new O2 sensors, air filter is clean, spark plugs only have a few thousand miles on them.

The temp today was 20 degrees hotter than the last time I dyno'd the car and humidity was less, but that would only account for maybe 5-10 WHP I think. Would a computer reset help at all? What could be causing something like this?

[-=Jeff=-]

I saw you have C6Z06 cats listed.. where did you find them at? were they a reasonable price?

[Billy Mild]

I saw you have C6Z06 cats listed.. where did you find them at? were they a reasonable price?

http://zr1.net/forum/showthread.php?t=21051&highlight=exhaust

I followed this thread about the cats. I purchased them used off of Corvette Forum for around $200. They are kind of heavy so shipping is what added so much money.

[XfireZ51]

http://zr1.net/forum/showthread.php?t=21051&highlight=exhaust

I followed this thread about the cats. I purchased them used off of Corvette Forum for around $200. They are kind of heavy so shipping is what added so much money.

Looks like your last run was your best run. What was the coolant temp for these runs? You should also ask them to use SAE correction and provide a graph using rpm instead of mph. In fact, I always request the run file so I can look at it on my own laptop.
And yes a leaner AFR will make a difference. Any change to timing?

**sorry bout that. I see the rpm scale on the other graphs.

[RussMcB]

Send the results (especially the AFR graph) to Marc and he'll know what changes to make.

Unfortunately it is an iterative process, but Marc is great to work with, so with some patience you'll get to where it should be.

Just curious - Before you saw the dyno numbers, how were you feeling about how the car ran? Did it feel like it was running stronger than a 4hp increase?

[Billy Mild]

Looks like your last run was your best run. What was the coolant temp for these runs? You should also ask them to use SAE correction and provide a graph using rpm instead of mph. In fact, I always request the run file so I can look at it on my own laptop.
And yes a leaner AFR will make a difference. Any change to timing?

Coolant temp according to my temp gauge is right about half way. The fans are programmed to come on at 205 and kick off at 200. I will request the runfile. I don't see why they wouldn't give it to me.

Would rich/fat tuning make for a much lower than expected HP number? I feel that only about 10 HP will be on the table with a leaner tune. Correct me if I am wrong.

Send the results (especially the AFR graph) to Marc and he'll know what changes to make.

Unfortunately it is an iterative process, but Marc is great to work with, so with some patience you'll get to where it should be.

Just curious - Before you saw the dyno numbers, how were you feeling about how the car ran? Did it feel like it was running stronger than a 4hp increase?

I was going to talk to Marc today on the phone and let him know what happened.

I haven't been romping on my car much since I got the exhaust done. I ran Marc's tune before I actually got the headers installed. It has been running so much better from a driveability standpoint. It is smoother everywhere. No hesitations in the powerband or anything. Pulls right up to Redline too.

Its hard for me to tell if my car is pulling harder than before only because it was a decent amount of time from when I drove it with stock headers than with SW headers and new exhaust. I would say yes, but I haven't driven it much. I got the headers on Friday, Saturday did the exhaust work, then Sunday was dyno day. I was running around tying up any loose ends to make sure I was ready for the dyno.

Guys, don't take this as me hating on Marc or anything of the sort. He has been great to work with thus far on my Throttle body and tune. I am going to call him today about the tune and see what his suggestions are. I'm just curious WTF happened to produce such a minimal increase for the exhaust mods.

[BigJohn]

A stock 375 hp with 15% lost in drive train is 318.65 hp at wheels.
389 hp with 15% lost in drive train is 330.65 hp at wheels.
393 hp with 15% lost in drive train is 334.05 hp at wheels.
Have you modified your intake before the throttle body?

[Jim Nolan]

I'm a little confused with your dyno sheet? Where is the RPM numbers. You could be running it in 5th gear at 100mph and I don't think you will reading the correct hp output. I originally had just plenum, injector housing and horn ported and stock exaust manifold with a corsa catback system with a Haibeck chip and put out 357.8 rwhp at 5300 rpm. That's when the hp started to drop off thru 7k. With the heads ported, cams reset, sw headers and dyno tune it put out 397.8 hp. The interesting part was that hp peaked out at 6500 rpm but never dropped off thru 7k. Can anybody chime in if I'm wrong? Good luck

Jim

[RussMcB]

Would rich/fat tuning make for a much lower than expected HP number?Yes! "Lean is mean". :-)

I feel that only about 10 HP will be on the table with a leaner tune. Correct me if I am wrong.Good question. I have a hunch, but don't know for sure. My car got a huge bump when I gave it to a tuner and they ran many dyno runs and making many adjustments. It would be interesting to hear a substantiated answer to that question. May be a good one to ask Marc.

[Billy Mild]

A stock 375 hp with 15% lost in drive train is 318.65 hp at wheels.
389 hp with 15% lost in drive train is 330.65 hp at wheels.
393 hp with 15% lost in drive train is 334.05 hp at wheels.
Have you modified your intake before the throttle body?

All runs were made in 4th gear except for 1. My car with just a modified airlid K&N filter and borla axleback exhaust with center resonator delete put down 330 WHP in the Fall of 2014.

Adding in Headers, high flow cats, x pipe, and Haibeck tune only managed to get 334 WHP. If you look at the dyno sheets one day was at 74 degrees(first dyno) and yesterday was 95 degrees(second dyno sheet).

I have done nothing for the intake or TB. The TB was polished by Marc in order to fix my sticky throttle blades.

[Billy Mild]

Yes! "Lean is mean". :-)


Lean is mean until you tune a 2 stroke, then it means tick tick, BOOM. LOL. Ask me how I know.

[BigJohn]

Sometimes the hose will compress and restrict air into throttle body.

[Billy Mild]

Sometimes the hose will compress and restrict air into throttle body.

I didn't even pay attention to that when it was being dyno'd as I was behind the car.

[Kevin]

if you have a factory duct that's not reinforced we found your problem

[Billy Mild]

if you have a factory duct that's not reinforced we found your problem

Is 330 RWHP and high heat outside the straw that breaks the camels back? The LT5 just has that much vacuum?

[Kevin]

Is 330 RWHP and high heat outside the straw that breaks the camels back? The LT5 just has that much vacuum?

squeeze the factory duct when it's hot and see how easy it is to collapse, it's terrible. I forgot how bad it is since I've had an upgraded one on mine for nearly the entire time i've owned it.

[cvette98pacecar]

Is 330 RWHP and high heat outside the straw that breaks the camels back? The LT5 just has that much vacuum?

Next time you go to the dyno take the accordion off, Let your beast breath.

[rush91]

if you have a factory duct that's not reinforced we found your problem


Wow I never even thought of that....mine is original. Where did you get your aftermarket one?

[Kevin]

Wow I never even thought of that....mine is original. Where did you get your aftermarket one?

I bought the last one that mark coplan had years ago at BG. Mark Haibeck, sells a solution that I would look at. Both keep the factory appearance and provide a more robust duct to keep it from collapsing. Coplan used a piece of aluminum inside the duct to keep it collapsing. Haibeck uses hoops. http://www.zr1specialist.com/HAT%20Web/products/hoops.htm that's a link for Habieck's one. Back when coffee cans were metal some people used those, cut up, to fit.

[Billy Mild]

http://www.jerrysgaskets.com/duct-silicone-air-inlet-black-red-blue-90-95-12a/

Jerry's makes a new one too.

[Paul Workman]

Yep! Been so long ago. I fashioned a liner out of sheet aluminum (smoooooth!) and pop-rivets. That solved my collapsing accordion - was choking out at 5500 rpm. No more!

[Kevin]

Didn't realized jerry made one. I'll add that to the mental list

[rush91]

I bought the last one that mark coplan had years ago at BG. Mark Haibeck, sells a solution that I would look at. Both keep the factory appearance and provide a more robust duct to keep it from collapsing. Coplan used a piece of aluminum inside the duct to keep it collapsing. Haibeck uses hoops. http://www.zr1specialist.com/HAT%20Web/products/hoops.htm that's a link for Habieck's one. Back when coffee cans were metal some people used those, cut up, to fit.


I didn't even think of that....Marc has done maintenance on my car a few times. I'll check tonight, I may already have some in there.

[rush91]

http://www.jerrysgaskets.com/duct-silicone-air-inlet-black-red-blue-90-95-12a/

Jerry's makes a new one too.


Wow, that Jerry's one looks very nice! Hmmmmmm choices :fahne:

[Billy Mild]

I spoke with Marc yesterday about the situation I faced Sunday on the dyno.

He mentioned if the shop didn't use SAE correction that the increased heat will have a bigger hit on the dyno numbers. After that he mentioned if my engine was heatsoaked that could have as much as a 10-15 HP hit. Those two things would make up about a 17-20 WHP affect on my dyno numbers. He said that I may be able to get 3% more power if he removed some fuel, but most likely that would not increase power much.

So overall it looks like outside temps, and engine temps may have hindered performance a bit. I will most likely wait for later this year when it cools down and dyno again to see if that is the cause.

[Kevin]

All of that is true and Mark would know better then anyone, however if you have the stock duct you need to change it out. Worth every penny of whatever option you go with

[mike100]

The very first time I took my headers out for the maiden voyage/test drive- I didn't feel a lot of difference, but he next morning in 60 deg air I could really tell. The torque at mid-range shifting into the next gear was much improved too.

initially I just ran the stock exhaust for about a month with the headers. Once I put the SW 3" catback on, then you could really feel more top end- at least in my case.

I have since discovered my secondary fuel pump wasn't maintaining pressure past 5500 rpm, but these days I am back to the oem manifolds. It runs a bit better on the stock pipes with the new pump- I kind of can't wait to try the headers again.

[Billy Mild]

Attached is my best run SAE corrected and with RPM instead of Speed.

[XfireZ51]

Attached is my best run SAE corrected and with RPM instead of Speed.

???

[Billy Mild]

http://i.imgur.com/i8LJ7jr.jpg

If anyone would want to look at the actual run file I can send that a long. Marc gave me some other suggestions such as maybe one of my secondaries is not opening all the way, could have a slight misfire as well. His test for misfiring is to go 40 MPH in 4th gear and go WOT. It should pull smoothly and clean.

Sent from my Nexus 6 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[mike100]

peak hp should be at 5900-6000 rpm and peak torque at 4800 rpm on the early 375hp engines.

[XfireZ51]

Here's an early stage mod dyno run on my car. Ported top end and headers.
As Mike points out, torque peak and hp peaks at higher rpms.
It makes me wonder if the cam timing may not need to be verified.

http://i187.photobucket.com/albums/x198/Z51Xfire/AzzuroFinalDyno.jpg (http://s187.photobucket.com/user/Z51Xfire/media/AzzuroFinalDyno.jpg.html)

[Billy Mild]

Looks like you are running closer to 13:1 for the AFR. I'm in the 11.8:1 range

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[Paul Workman]

http://i.imgur.com/i8LJ7jr.jpg

If anyone would want to look at the actual run file I can send that a long. Marc gave me some other suggestions such as maybe one of my secondaries is not opening all the way, could have a slight misfire as well. His test for misfiring is to go 40 MPH in 4th gear and go WOT. It should pull smoothly and clean.

Sent from my Nexus 6 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

Yep. That ain't right!

Here is another set of dyno graphs, one w/ 2ndaries closed and then open (the porting specifications unknown). Notice where your torque is peaking compared both Dom's top-end porting graph, and the one from Lingenfelter.

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/LT5ptopenvsclosed_zps79a8b9ce.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/LT5ptopenvsclosed_zps79a8b9ce.jpg.html)

You can see why Marc is wondering if the secondaries are opening properly. Although skewed somewhat toward FULL POWER, the graph stubbornly follows the primary characteristics. Cam phasing might be a small part of you graph, but it does look more like malfunctioning secondaries.

Again, Dom's top-end graph for comparison...


http://i187.photobucket.com/albums/x198/Z51Xfire/AzzuroFinalDyno.jpg (http://s187.photobucket.com/user/Z51Xfire/media/AzzuroFinalDyno.jpg.html)

Yours should look more like Dominic's graph for a top-end/headers upgrade.

[Billy Mild]

My secondary vacuum doesn't run very when the isn't running. Once a minute or so.

My top end is stock. No porting of any kind. I would be shocked if the cam timing has been changed. Records that came with the car made no reference to that. If my secondaries weren't opening all the way is there a way to check that without pulling the plenum?

Sent from my Nexus 6 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[RussMcB]

Somewhere I read you can observe the servos opening without removing the plenum by just peering down into the valley while tricking the system into opening.

It is sort of implied at the end of this article:

http://www.zr1specialist.com/HAT%20Web/articles/Finding%20and%20Fixing%20Vacuum%20Leaks%20on%20the %20LT5%20Engine.pdf

[XfireZ51]

As an FYI, cam phasing will change due to slippage of the sprocket and chain stretch over time.

[bdw18_123]

As an FYI, cam phasing will change due to slippage of the sprocket and chain stretch over time.

And, according to Marc, the factory method of setting the timing is "subject to variation". According to his timing article, his '93 LT5 was found to have the left exhaust cam set 4 degrees out of phase with the others. So cam timing is definitely something worth checking, though it is far from an easy process.

http://www.zr1specialist.com/HAT%20Web/articles/Camshaft%20Timing.pdf

[We Gone]

Somewhere I read you can observe the servos opening without removing the plenum by just peering down into the valley while tricking the system into opening.

It is sort of implied at the end of this article:

http://www.zr1specialist.com/HAT%20Web/articles/Finding%20and%20Fixing%20Vacuum%20Leaks%20on%20the %20LT5%20Engine.pdf


The how to is in Dynomites sticky. You can also do this with a flashlght. he has so much information I could not find the exact link.

http://www.zr1.net/forum/showthread.php?p=187361

[mike100]

My car also ran 13.1 AFR with a cat-back and a chip as measured at the muffler with the external wideband.

These cars run rich and don't need much fueling change to accommodate the usual bolt-on's...why is yours so rich?? I would still check fundamentals like the fule and spark, but also the possibility that the intake duct is collapsing limiting you to 5500 rpm pulls and cutting off the air part of the air-fuel ratio. Either that or you got a bad muffler or something very unconventional happening.

[Billy Mild]

I did a little test drive today around town. The car seems to run pretty well overall.

Marc told me to perform a test to see if the car is misfiring at all. Do a WOT pull from 40 MPH in 4th gear. It should pull cleanly without any hesitations or issues. When I did this in Open loop before the car was fully warmed up I did notice a bit of a hiccup right at the beginning, but it overcame that.

When I did the same test fully warmed up the car pulled without issue. Even when the car is warmed up I heard a bit of gurgle coming from the exhaust when decelerating. I'm curious if that points to anything or if these cars should sound like that.

On my scanner I saw the BLM at 133-136 when at idle, but it was 126-129 while driving. I didn't get to see what it said when at WOT. I need to get a datalogger or at least TunerPro with a ALDL adapter.

[Hog]

WOT info doesn't mean much from the narrowband O2 sensors as it will read rich. For accuracy the wideband is needed.

It would have been nice to be able to compare some 1/4 mile speeds as compared to mods.