Driver impressions from those who did some porting please [Archive]

billschroeder5842

01-14-2018, 01:39 PM

Hey all, I like "driving impressions" (not so much of a technical discussions on how our cars respond to some minor work.

I have a '91 that is bone stock except for a Haibeck chip and a MagnaFlow low restriction resonator. I drive the car about 3-4 times a week and would be described as the occasional "spirited" driver. No tracks, no racing but more of a cruiser that will wind it up to 7k rpms on the interstate on-ramp. I take dependability over performance.

What im considering is porting the plenum, adding headers with lower (probably a Corsa) restriction exhaust, new injectors and a decent tune. My guess is about $5800-$6500 all in.

So,
What is the car going to "feel" like? Better/more low end torque? Of is this a midrange or higher RPM combo? Are there any "unforeseen" reliability or maintenance issues? Is it worth the bang for the buck for my driving style of "dependable with an occasional punch?"

I'd appreciate anyone's thoughts from somebody who has "been there and done that..."

efnfast

01-14-2018, 01:51 PM

If you like hp, there is no downside.
The only mod I'm on the fence about is installing reground cams. Not sure the driveability was worth the hp gains

Demps

01-14-2018, 02:11 PM

I drove a stock car for two years. Saved my money and got a B&B. Thought I was in heaven...until I added headers and Aaron Scott at SGC graciously helped me with a chip. Then I was in heaven. That car dynos at 390 SAE ('95). Stock gears so real power is up top.

Those that know me realize I can't leave well enough alone. I rode in some strokers and was bitten. I even had the privilege of a very good friend allowing me to drive an LPE bodied 415. Well that cost me but well I've gotten off track. Back to what you asked...

In between I traded for a Haibeck 350 (422 rwhp) with 4.10 gears. I think that's about perfect--stock bottom end with gears. I personally think I would like 3.9x gears better but harder to come by. Marc is getting closer to 430 rwhp now with the full deal and stock cams. I personally would stay with stock cams by the way. (Can give reasons if desired).

So, ported top end (plenum & injector housings), tune, headers, good exhaust of choice and you will be in the 390-400 range. That's good! I have a spread of ZR-1s from stock to wild. I would strongly recommend you send the car to Marc or Corey (but I've heard he isn't doing them anymore) and go all inclusive with a full 350 package plus gears. Marc will return the car better. Porting the heads too will get you a car that you now want to drive seven days a week and twice on Sundays.

If you're ever in the Panhandle of Florida we can stroll through stock, bolt ons, porting, porting with cams, 385, & 415.

Ted

XfireZ51

01-14-2018, 02:20 PM

IMO, ported top end is how the car should have come from factory. Careful however, because it will lead you to the "dark side". 398rwhp/358rwtq.
Intoxicating.

Top Toy

01-14-2018, 06:51 PM

Best bang for your buck, IMO, would be headers, low restriction exhaust and 4.10 gears. Next would be porting the plenum and injector housings. This combo alone will double the width of your grin!

efnfast

01-14-2018, 07:48 PM

I did mine piece by piece, I'm sure it cost me way more than the 10 grand Marc charges.
Just a thought.

RichS

01-14-2018, 08:12 PM

I bought mine with just a chip and catback. I thought it ran ok but nothing crazy. (I did find I had a bad fuel pressure regulator stuck at 52) I did 4:10's, short shifter, tires, suspension bushings, lowered, rear shocks, brakes ect. It ran better but was still like ehhh? Took my wife for a qick ride and she said "that's it?" (FPR was still at 52) ( We have had a few supercharged C6s one was 550rwhp, one 725rwhp)

Then I pulled the motor, had the heads, intake and inj housings ported, did regrind cams that Lee helped me with, Headers and a different cat back. Now the car feels like I thought it should. Pulls real hard in the upper rpms, but still pulls nice down low. Drives and idles like stock, no drivability issues. Very happy with the car.:cheers:

RussMcB

01-14-2018, 11:59 PM

Paul Workman

01-15-2018, 06:36 AM

Ported my top end and blended the heads (port matching on steriods), Stainless Works headers & X-pipe, Mangnaflow mufflers, 3" exhaust. With Mark's chip and stock cams and TB it put 400 (est) to the ground with zero loss of drivability!

It completely changed the personality of the car - loved it! Loved it so much that the following winter I ported my heads - finishing the porting - except for th TB. Pete phased the cams and Marc did a dyno tune; boosted rwhp to 432. It has practically a stock idle and is a total SLEEPER!

There is NO downside what so ever. As someone said, "They should have come that way!" Can't quite find the words to describe the expression on the face of a local C6 driver after I pulled away from him on the expressway before letting up to let him catch up to cruise along side. Kinda look of puzzled surprise (Heh, heh, heh. (Yeah, that's right, buddy...a "stock" sounding C4 just walked away from ya - like it was nothin'!)

WARP TEN

01-15-2018, 10:05 AM

Hi Bill--
I'll chime in here as well. The difference between 375 HP and 510 or so is very impressive. You probably don't need the much greater expense of cams; I certainly was perfectly happy with stock cams, but that is personal choice. With 510 HP the car is quite controllable and easy to drive around town, but a real rush when you get into it. Mine ran 12.4/116 at Beech Bend--not bad for 30 year old technology. If you like the idea of more power as I do (see Mickey Thompson quote below), you will be very happy to have done the mods. One big plus is that the engine can look perfectly stock if you like that, as I did.

But I will also suggest, as have others, that you talk with Marc Haibeck about having him do the work. He and son Bob have done so many of these that he knows all the tricks and also will thoroughly examine the car to see if any other things need doing. (I did 4.10 gears and a Hurst shifter, both of which I recommend).If you like doing these kind of mechanical tasks yourself, fine, but there is a lot involved in getting 500+ HP out of these engines. A lot of little details that need to be gotten right. For a little extra cost premium it was worth it to me to have the world's expert on these engines do mine. If you have not yet, I recommend a read through Marc's Website (www.zr1specialist.com) for a description and cost on the kinds of mods you are thinking of. And a chat with him on the phone might be helpful in your decision making. He always makes himself available to talk to people.

And if you decide to have him do the work, lets us know when you might be coming up and we can have lunch with a few of the FBI guys. Good luck on your decision. Either way you'll be happy with the results.-Bob

efnfast

01-15-2018, 11:20 AM

There are a couple guys out there that do very good work on these engines. Marc being one of them.
Pete did the heavy lifting on my car. Again, doing it piece meal, I'm sure I've got more than the 10 or so grand these guys all hover around.
I'm 451 at the wheels. Wife doesn't like the car anymore, can't wipe the grin off my face.

XfireZ51

01-15-2018, 11:58 AM

I just posted a .pdf on my thread re:Tuning the LT5. You will find a comparative dyno sheet there that shows the diff in hp and torque between three successive upgrades that I did on my car. Should give u a benchmark on the Cost/Benefit of each. OTOH, there are some that don’t care about cost/benefit. We just want to eek out as much power as possible. :proud:

Kevin

01-15-2018, 12:01 PM

drove my car, got out, hopped in a ported car that made 440 wheel. night and day. no downside, all up. If I had the money I'd have it done already

PhillipsLT5

01-15-2018, 04:15 PM

422RWHP all good no cons no buyers remorse

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We Gone

01-15-2018, 05:05 PM

Just do it. took me 10 years to get it done no regrets :fahne:

GOLDCYLON

01-15-2018, 08:46 PM

billschroeder5842

01-15-2018, 09:22 PM

Thanks guys- this is what I'm looking for. From what I'm reading, a 4.10 gear, porting the tops and headers are a low risk , super high (fun) return on investment.

XfireZ51

01-15-2018, 11:25 PM

Thanks guys- this is what I'm looking for. From what I'm reading, a 4.10 gear, porting the tops and headers are a low risk , super high (fun) return on investment.

U got it.

Kevin

01-16-2018, 12:42 AM

Thanks guys- this is what I'm looking for. From what I'm reading, a 4.10 gear, porting the tops and headers are a low risk , super high (fun) return on investment.

The downside is having to buy rear tires more often.

-=Jeff=-

01-16-2018, 09:02 AM

I will agree with the 4.10s making the car fun. but my car is still not ported and honestly, no plans to port any time soon

billschroeder5842

01-16-2018, 09:25 PM

So, (insert strong opinions here) for a header back exhaust what is everyone's experiences? I read, read with more reading with the conclusion being that Corsa is the one to have coupled with either Henderson headers or SW.

I Like a bit of rumble and burble on deceleration but drone is a super no-no. Plus, I want the idle to sound "Corvette" and not 69 Hemi Super Bee.

I listen on you tube and Borla sounds more what I like(ish) but the drone has me

I kind of like cars that are a "sleeper" in presentation.

Kevin

01-16-2018, 10:21 PM

corsas are they way to go if you like the sound. It's grown on me

efnfast

01-17-2018, 06:09 AM

You really have to come to Bowling Green and listen to some cars to decide.
I have ceramic coated OBX headers and OBX exhaust. Very happy with it.

Paul Workman

01-17-2018, 06:56 AM

My rule of thumb is, if you floor it more than once in a while (and for more than a second), and then think, I don't have enough HP, then maybe consider spending money (thousands of dollars).

I have (non ZR-1) friends that never see redline yet think they need to buy go-fast goodies.

Boy...ain't THAT the truth! Approx. 40% of ZR-1 owners too, according to a now old poll, have never got much above 6000, if that.

dredgeguy

01-17-2018, 08:12 AM

randy ransome

01-17-2018, 11:29 AM

Boy...ain't THAT the truth! Approx. 40% of ZR-1 owners too, according to a now old poll, have never got much above 6000, if that.

Every time I leave the house in my Z I go past 6 grand several times before the day is over...I thought that's what these car were for, Fun.

:proud:

Gunny

01-17-2018, 12:32 PM

I kind of like cars that are a "sleeper" in presentation.

For the "sleeper" idea, consider this ...
4:10, porting, headers, and late C4 stock exhaust with electric cutouts. Try to locate a 95 stock ZR-1 exhaust or a 96 LT4 exhaust. Install a pair of QTP electric cutouts just ahead of the muffler inlet. The cutouts are controlled by a switch located to your convenience. Totally open it's very close to running open headers - totally closed it's almost stock sounding (headers add a nice touch) - partially opened to taste, you can pick the sound that you like. Drone is only present when you open more than half-way.

I've had the stock system on my 90, 2.5" Borlas, 2.75 Borla Challengers, Corsas, stock 95 exhaust, and finally the stock 96 LT4 w/cut outs, SW headers, and porting by Marc.

Highly recommended: listen to & ride or drive as many Z's with different setups before you start modding your exhaust ... it will save time & money in the long run.

Paul Workman

01-17-2018, 03:08 PM

Here's mine idling, fully ported w/ stock cams...

https://www.youtube.com/watch?v=y1YFa8ruh8A

Below is my stock 90 ZR-1 (RED) and the fully ported version (BLUE)- as you see it in the video (above).

.

32valvesftw

01-17-2018, 04:48 PM

Bill, I am running Bolas, Henderson headers, no cats, and an X pipe in place of resonator. It is loud and has that BRAAAAP on acceleration, but it does drone in 6th at legal speeds. I do not know if mine is ported, I doubt it, but after Corey did the headers she dynoed at 383 WHP. Drop me a line if you are close by Houston and swing by and you can hear it in person. I personally do not get the full experience from youtube, To me it's kinda like trying running a brothel with pictures!

jss06c6

01-17-2018, 08:41 PM

Bill,

You rode in my '91 in Buffalo, Tx at our last gathering. 100% Stainless Works headers to exhaust tips. I do have drone at 1800 RPM, gone by 1900 RPM. Exhaust note is great. I'm about to port a plenum and injector housings, then port match the heads and retune (my tune). Currently #473 is putting down 359, 350 at the wheels with only headers and tune.. will let you know what I find with the top end porting on my '91.

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WARP TEN

01-18-2018, 11:09 AM

For the "sleeper" idea, consider this ...
4:10, porting, headers, and late C4 stock exhaust with electric cutouts. Try to locate a 95 stock ZR-1 exhaust or a 96 LT4 exhaust. Install a pair of QTP electric cutouts just ahead of the muffler inlet. The cutouts are controlled by a switch located to your convenience. Totally open it's very close to running open headers - totally closed it's almost stock sounding (headers add a nice touch) - partially opened to taste, you can pick the sound that you like. Drone is only present when you open more than half-way.

I've had the stock system on my 90, 2.5" Borlas, 2.75 Borla Challengers, Corsas, stock 95 exhaust, and finally the stock 96 LT4 w/cut outs, SW headers, and porting by Marc.

Highly recommended: listen to & ride or drive as many Z's with different setups before you start modding your exhaust ... it will save time & money in the long run.

Bill, George is right--If you like a sleeper look but the ability to add power and be very loud when you want it, go for headers (with or without cats), a stock '95 system with cutouts. I used Corsas for years and they had a great sound and were the best to minimize drone, but in my old age I got a little tired of a loud exhaust all the time. This allows you to be almost as quite as stock (which still sounds pretty good) when you want it, but loud and open for power when you want it also. Allows you to preserve the spare tire carrier which I wanted. Based on Tony Davila's idea, I had Marc H. install mine right in front of the stock mufflers with a rocker switch hidden under the carpet on the passenger side of the console within easy reach. Relatively quite when closed, and basically straight pipes when open. I usually ran about one third open for some solid rumble. Wide open for racing and when I wanted to scare pets and small children. Here are a couple of pics--I have more pics if you decide to go this route. There is a video on my YouTube page of me running at NCM Motorsports park with them open if you want to hear what they sounded like. Here is a link: https://www.youtube.com/watch?v=DBwKZrENBS0&t=615s --Bob

-=Jeff=-

01-18-2018, 11:19 AM

Bob,

what do you mean by 1/3 open? 1/3 of of the time? or was it an adjustable cutout?

WARP TEN

01-18-2018, 11:23 AM

Bob,

what do you mean by 1/3 open? 1/3 of of the time? or was it an adjustable cutout?

Hi Jeff--
Yes, the cutouts were adjustable via the switch and electric motors on the cutouts. You can see the bottoms of the motor cans above the cutouts in the second picture in my post. My wife wanted the car quite when I was within our subdivision so I closed them when coming home or leaving. But then opened them up a bit if I felt like a little bit of loud exhaust. Usually about 1/3 open (I am guessing here) provided the right amount of sound for me. --Bob

-=Jeff=-

01-18-2018, 11:27 AM

Do you know what brand the cutouts were?

Thanks

WARP TEN

01-18-2018, 11:51 AM

Do you know what brand the cutouts were?

Thanks

Yes they were Quick time Performance or QTP cutouts which I think we got from Summit. I also added the little extension downturn which I painted flat black. Wanted to direct exhaust somewhat way from the tires, even though it is not too hot by the time it gets back there. The switch they send with them is just a big toggle switch which I didn't like so the rocker switch is my invention and worked well. There is a discussion of the switch installation and more pictures on a different thread here. Here is a link on the switch but there are lots of threads on cutouts. http://www.zr1.net/forum/showthread.php?t=25554&highlight=cutouts --Bob

Gunny

01-18-2018, 01:17 PM

After reading Tony's writeup about his cutouts and seeing Bob's installation I had a pair of QTP cutouts installed just before the muffler inlets. A good exhaust tech can make the QTP fit very nicely with a short turndown pipe (painted black) that is very difficult to see unless you lean down and are looking for it. Marc placed the toggle switch in an area aft of the emergency brake lever ... it's essentially hidden but easily accessible with the left hand. The toggle switch is a DPDT self centering switch ... hold it up to open the cutouts/down to close. It's very easy to open/close the cutouts to any position between fully open or fully closed.

I'm running headers/no cats with the stock 96 LT4 exhaust ... the resonator is said to be the most free flowing of all the stock C4 exhausts plus there is a balance tube (H-pipe) behind the resonator. My system totally closed sounds good (at least to me) probably because of the headers/no cats and only gets better as you open the exhaust up. I'm guessing that my best sound with no drone is somewhere between 1/3 & 1/2 open ... beyond that, the dreaded 6th gear drone becomes a factor; but when I'm running totally open, I rarely use 5th or 6th.

Like Bob, I tried other systems and even liked them, until the sound and/or drone became too much. For me this provides the best solution. btw, this setup can provide huge grins, especially in enclosed parking garages :rolleyes:

-=Jeff=-

01-18-2018, 02:01 PM

Gunny, how is the odor from having no cats? I found it a bit much on my Borla challenge system and I have cats with Corsa currently

Gunny

01-18-2018, 02:22 PM

no odor detectable above 70 mph :mrgreen:

in retrospect I probably should have used some high flow cats. I don't have a good sense of smell so it doesn't bother me much; but when I'm leading a caravan, those behind me with sensitive noses have complained. I imagine I will add the cats back to solve that issue ...shouldn't hurt the sound any nor have too much negative impact on HP/torque

-=Jeff=-

01-18-2018, 06:57 PM

Thanks Gunny, I just snagged a LT4 system locally. Now to get it installed with my C6Z06 cats

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Gunny

01-18-2018, 07:01 PM

Let me know how that works out. I think the C6Z cats are a good idea ... wouldn't mind scoring a pair for my setup. Take pics of the install.

Ccmano

01-18-2018, 08:03 PM

The trick is finding an LT4 system. Z06 cats are easy.
H
:cheers:

XfireZ51

01-18-2018, 08:33 PM

Gunny, how is the odor from having no cats? I found it a bit much on my Borla challenge system and I have cats with Corsa currently

Jeff,

Currently tuning Hans’ 90 w similar setup. Working on tuning out most of the rich smell which is typical at idle. We’ve been able to reduce it significantly.

billschroeder5842

01-18-2018, 09:03 PM

Bill, George is right--If you like a sleeper look but the ability to add power and be very loud when you want it, go for headers (with or without cats), a stock '95 system with cutouts.

Wow, what a slick system- I bet that is a lot of fun!

XfireZ51

01-19-2018, 12:00 AM

Wow, what a slick system- I bet that is a lot of fun!

Some of us here in the Windy are using the C6Z06 NPP valves mated to DynoMax Ultraflow muffs. I have a switch in the center console controlling Open/Close on these. I mostly drive w them closed. Even w/o resonator, they do a good job of controlling drone IMO. Especially w better tuning.
W the valves open, everything still goes thru the muffs but now a second opening is operative giving the exhaust a deeper bass note much like a big block.

WARP TEN

01-19-2018, 10:24 AM

Gunny, how is the odor from having no cats? I found it a bit much on my Borla challenge system and I have cats with Corsa currently

There was definitely a strong odor in the garage on start up but as Gunny notes, not at 70 mph. Marc reminded me that it is what cars smelled like in the 60s and 70s. I think if i still had the '95 I would add some bullet cats or maybe the Z06 ones noted elsewhere to minimize this. --Bob

WARP TEN

01-19-2018, 10:27 AM

Wow, what a slick system- I bet that is a lot of fun!

For me it was certainly the perfect system and I did enjoy it. Always fun to be sitting quietly at a light then open up the cutouts. Or starting the car with the cutouts open, say when you are leaving a car show.--Bob

-=Jeff=-

01-19-2018, 03:08 PM

Jeff,

Currently tuning Hans’ 90 w similar setup. Working on tuning out most of the rich smell which is typical at idle. We’ve been able to reduce it significantly.

Understood, but it is still there. I have almost all the pieces, i just need to make them all fit together

rush91

01-19-2018, 05:30 PM

Bill, you just couldn't leave it original huh lol.......Mods on these cars are addictive. Once one starts, it's hard to not keep going! I plan on making it to Bowling Green this year for the Gathering, and plan on asking you guys with Mods ALOT of questions!!! And maybe ask for some ride alongs, to get a feel for the different exhaust / header combos.......Ya, I'm going to be that guy who asks a million questions lol.