Took my 91 ZR-1 to the dyno today

[Neat]

Made a trip to RPM Motorsports in Garner, NC today to strap my 91 ZR-1 to a dynojet 224 chassis dyno.

We made 3 pulls with the power key set to "full" and one pull with it in "normal" mode. The car made 371 RWP / 354 RWTQ on the third pull. All three pulls were within a couple HP of one another. With the valet key on sissy mode, the car only made 239 RWHP. Over a 100 HP difference, it was pretty wild to see the difference quantified like that.

It's kind of a weirdo car in terms of mods; it has:

DRM intake cams
Extrude honed plenum
Haibeck chip
Borla catback

It's still on the stock exhaust manifolds and catalytic converters, which is probably holding it back some. Overall though, I'm very pleased with the car.

PS - the guys at the dyno had never seen an LT5 before. They were impressed with the car, and were shocked when I showed them they could turn off 132 RWHP with the little key in front of the shifter.

Here's a video, the car sounds amazing in my opinion:

https://www.youtube.com/watch?v=WGcS93uVtBg&feature=youtu.be

I was sort of surprised / impressed by how little the engine moves when making a pull. It was ran from 2000 (or so) to 7K, and if you watch the engine in the video it doesn't wiggle, rare up on the drivers side, nothing. With no audio and not being able to see the back tire, I don't know that you could tell the car was even running.

[lfalzarano]

I tried to use them for work on my Z, but they are only interested in add-ons and not maintenance.


Lou

[Neat]

I used to work there 5-6 years ago, I’m still pretty good friends with the crew there. The older stuff is definitely outside their comfort zone; they don’t have any of the gear to flash chips, data log OBD1 stuff, etc... Primary focus is LS stuff for sure.

[Ccmano]

Nice... tho the extruded honed Plenum doesn’t accomplish much. You really need a full top end porting of the plenum and injector housings to get the most out of it. Even with the stock exhaust manifolds your set up (properly ported) should be around 400rwhp considering you have cams.
H
:cheers:

[Neat]

Nice... tho the extruded honed Plenum doesn’t accomplish much. You really need a full top end porting of the plenum and injector housings to get the most out of it. Even with the stock exhaust manifolds your set up (properly ported) should be around 400rwhp considering you have cams.
H
:cheers:

Just want to be sure you and I are on the same page: The car only has intake cams, the exhaust cams are stock.

You still think it'd pick up that much with the port work on the intake?

[Ccmano]

Yes I do. Based on my observations, generally, LT5’s with Plenum/IH porting, headers and a good tune get in the 390’s. Add head porting and a light flywheel and they are in the 415-425 range. (Rwhp)

Your combination (without headers) with proper Plenum/IH porting and a custom tune should get you at least 20hp. There was a write up about Extrude Hone here somewhere a few years ago. It was found that it did not significantly open the plenum runners. Let alone the injector housings that can be opened considerably. While some have gone farther, current thinking is to open the Plenum, Injector housings and into the head to 36mm for both primary and secondary runners.
H
:cheers:

[Neat]

I’ve read the Haibeck articles on porting, it was something I have always intended to do... For whatever reason though, your comments have moved that particular project a little closer to the top of the to-do list!

[LGAFF]

I have a DRM car w/o the intake cams. The Borla chokes it with a 2.25" resonator choke point, the etrude honing is pretty small, but will compliment an updated port job. With some updated porting, headers and Xpipe to remove the resonator I made 391RWHP

[mcich7781]

Josh,

Check the DRM invoice. I believe this car was already ported. It got the full DRM 475 treatment, bigger throttle body, porting, intake cams.

Headers were left off at that time for reasons we have already discussed.

Mike.

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Neat]

I’ll do that, thanks Mike!

[Ccmano]

If that’s a DRM475 I would be hugely disappointed in 371rwhp. A 475hp motor should have 400rwhp.
H
:cheers:

[Neat]

It is a DRM 475 car. However, it's missing the headers that normally come with that package. I'm not sure how much power is being left on the table by continuing to use the stock exhaust manifolds.

The dyno numbers were about what I expected, and certainly not a huge disappointment, lol. It would interest me to install some headers and do the dyno test again. I'm curious how much (if any) stock manifolds are costing me. Maybe that'll be the next "to do" thing for the car.

[efnfast]

I would think headers would get you to about where Hans expects you to be.

[ZWILD1]

I was surprised to see that your car is the same color exterior and interior as mine. Plus I just installed the chrome five spokes about a week ago with BFG drag radials and the BFG Comp II summer tread up front. Mine was done by Mark Haibeck with the 525 package so there is no limiting the power via the Valet key. It's not like my first 91 that had headers , no cats, B&B 3in exhaust , and 4.10 gears. It still delivered descent gas mileage with the secondary actuators still working. With the Haibeck 525 package when you stomp on it you can almost see the fuel gauge go down, lol.

[jss06c6]

It is a DRM 475 car. However, it's missing the headers that normally come with that package. I'm not sure how much power is being left on the table by continuing to use the stock exhaust manifolds.

The dyno numbers were about what I expected, and certainly not a huge disappointment, lol. It would interest me to install some headers and do the dyno test again. I'm curious how much (if any) stock manifolds are costing me. Maybe that'll be the next "to do" thing for the car.
Assuming a proper tune, I would suspect about 25-35 WHP loss by using the stock exhaust manifolds. They are severely pinched at the collector and definitely a source of exhaust restriction.

Sent from my QTAIR7 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)