Opel GT Forum banner

Who will win the dyno challenge?

  • Jeff will have more hp and more torque

    Votes: 0 0.0%
  • PJ will have 200+ hp

    Votes: 0 0.0%
  • Jeff will have 175+hp

    Votes: 0 0.0%

  • Total voters
    13
41 - 60 of 63 Posts

·
Opel Intern
Joined
·
1,290 Posts
Agreed PJ. One of the racing forum members here dynoed his car, made 160 hp at the rear wheels. The dyno operator rejetted the carbs and played with his ignition timing, he got up to 181 hp at the rear wheels in 30 minutes. Even if it cost him $300, that's the cheapest 20 HP he's ever paid for! I guarantee the first 160 hp cost him $6000 or so.
Granted, he did pay for the potential to have that last 20 HP with at least some of the first $6k! :)

I think most anyone can tune 80% of their engine performance just with their nose and seat of the pants feelings. But to make any real amount of power or true maximum economy - as in any true 'performance' of the engine - a dyno with an operator who knows how to use it is the only way to truly maximize all of the gains.
 

·
Super Moderator
Joined
·
13,249 Posts
Granted, he did pay for the potential to have that last 20 HP with at least some of the first $6k! :)

I think most anyone can tune 80% of their engine performance just with their nose and seat of the pants feelings. But to make any real amount of power or true maximum economy - as in any true 'performance' of the engine - a dyno with an operator who knows how to use it is the only way to truly maximize all of the gains.
Actually, if you think about it, the first 80 whp (stock engine) or so is free, so the next 80 whp cost $6000. Gaining 21 whp on top of that is HUGE for the money invested.
 

·
Registered
Joined
·
2,613 Posts
Actually, if you think about it, the first 80 whp (stock engine) or so is free, so the next 80 whp cost $6000. Gaining 21 whp on top of that is HUGE for the money invested.
I have around 500 dollars invested in my TR6 head.

High comp head from a parts engine, ported it myself so I'm not including the cost of the tools, only cutters and stones, but I've replaced valves and guides and had the seats professionally re-cut

I'm *hoping* to get around 20 hp (105 to 125 hp on a 2.5) out of that upgrade, ported and CR bumped from 7.5 to 9.5, but that also includes 500 dollars worth of headers and some further porting of the intake.

I'll take those 20 hp for 500 dollars, or 300 if I can get it, because even this budget build will have cost me at least twice that amount by the time I get it bolted to my engine.
 

·
Senior Contributor
Joined
·
4,914 Posts
Yup. This discussion caused me to send an email to EFI Logics to see if they would quote an estimate to tune my GT. Waiting to hear back from them.
So I spoke to the guys at EFI Logics and I can't say that I am comfortable with bringing the car there. After I explained to Cory (the tuner who has worked with MegaSquirt on a Miata or two) what I wanted to do his answer was, yea I'll take a crack at it. So if anyone knows of a good dyno tuner dude within about 2 hours of 10507 let me know. I will have to start calling around too.
 

·
Super Moderator
Joined
·
8,154 Posts
So I spoke to the guys at EFI Logics and I can't say that I am comfortable with bringing the car there. After I explained to Cory (the tuner who has worked with MegaSquirt on a Miata or two) what I wanted to do his answer was, yea I'll take a crack at it. So if anyone knows of a good dyno tuner dude within about 2 hours of 10507 let me know. I will have to start calling around too.
I'd tell him the problems I'd been having and ask what kind of results I could expect from his tuning. I know he can't guarantee how much improvement you'll see but I would think that he would have a better idea after he drove the car.

Harold
 

·
Just Some Dude in Jersey
Joined
·
13,987 Posts
Discussion Starter #46
It's a bit farther than your stated limit, but there's always my dyno guy in Philadelphia. He's from Greece, his whole family had Opels, and he's dyno'd and tuned mine. What more could you want? A foreign guy who grew up around 4 cyl cars and has prior experience with Opels and has a dyno shop. His lot was filled with street rods and performance cars.

Collingdale Performance.

:veryhappy
 

·
Senior Contributor
Joined
·
4,914 Posts
It's a bit farther than your stated limit, but there's always my dyno guy in Philadelphia. He's from Greece, his whole family had Opels, and he's dyno'd and tuned mine. What more could you want? A foreign guy who grew up around 4 cyl cars and has prior experience with Opels and has a dyno shop. His lot was filled with street rods and performance cars.

Collingdale Performance.

:veryhappy
I just sent them an email, thanks for the tip.
 

·
Opeler
Joined
·
3,606 Posts
After dyno testing few weeks ago, I have been told that my mix was too rich which prevents the engine to develop full power. My pride was hurt. I have years of experience with DSD carburetors and was always able to properly tune them. Why are they so “off” this time?

My cat Nelson woke me up early this morning. I was still in bed when the thought crossed my mind: What if the air filter is clogged? After feeding Nelson, I went to the garage and removed the filter. Tried the car on a closed course but could not notice any difference. Hmm?. Think again: I am using Dbilas air box that I heavily trimmed in order to fit in the engine bay. It worked fine with my previous 2.0 engine but what if it is choking my heavy breathing 2.5 engine? Removed the air box and fit some velocity stacks that I had in the parts stash. Took the car for a test and could not believe the difference. Here is short video.

I have scheduled second dyno test next week, just to prove that my seat-of-pants tuning skills are still working.

http://www.youtube.com/watch?v=jxCu0bvi2U0&feature=youtu.be
 

Attachments

·
Super Moderator
Joined
·
13,249 Posts
I am using Dbilas air box that I heavily trimmed in order to fit in the engine bay. It worked fine with my previous 2.0 engine but what if it is choking my heavy breathing 2.5 engine? Removed the air box and fit some velocity stacks that I had in the parts stash. Took the car for a test and could not believe the difference.
You have 'discovered' what Conrero discovered 45 years ago...the Opel GT doesn't have enough room under the hood for good airflow to DCOE carbs!
 

·
Registered
Joined
·
1,683 Posts
That's one Rev happy 2.5 stroker you have there P.J.! :veryhappy
 

·
Registered
Joined
·
1,683 Posts
I've been analyzing your awsome video. What a powerful and impressive power plant you ve built.

Is it safe to say your 0-60mph is around 7.5 sec and your 0-100 is around 19 sec?

Really happy you posted it as it's an interesting comparison to my 2l acceleration video. You clearly make 60+ hp more then me!:cool:
 

·
Senior Contributor
Joined
·
4,914 Posts
I've been analyzing your awsome video. What a powerful and impressive power plant you ve built.

Is it safe to say your 0-60mph is around 7.5 sec and your 0-100 is around 19 sec?

Really happy you posted it as it's an interesting comparison to my 2l acceleration video. You clearly make 60+ hp more then me!:cool:
Sounds to me like he could shave off another second with faster feet and hands :yup:
 

·
Opeler
Joined
·
3,606 Posts
I measured the best result 0-100 km/h in 6.6 sec measuring with Speedhut GPS speedometer.

The numbers are actually less important to me. What I am really pleased is how that engine turned out. My goal was to make strong engine that can still be driven normally under street conditions. I even kept hydraulic lifters. ENEM cam was recommended by Jan Carneborn and it is perfect match for 2.4/2.5 engine. Some high end components are used mostly for the reliability reason. A week from now I will drive to OctOpelfest, another 1200 miles round trip at much slower speed than on the video. It will also be interesting to check the fuel consumption without that restricting air box.
I would still have to design some kind of properly sized air box over the carbs in order to contain the noise. As the season is closing to the end, that will be the winter project.

P.S. Just received an email from local buddy: Just posting it on Youtube may be enough to get you convicted. Opel GTs are not that common and you are developing a reputation.

Should I remove the video?
 

·
Super Moderator
Joined
·
8,154 Posts
P.S. Just received an email from local buddy: Just posting it on Youtube may be enough to get you convicted. Opel GTs are not that common and you are developing a reputation.

Should I remove the video?
First of all it was in KPH, IIRC and secondly it was on a closed course I'm sure where it was legal. :)

JM2CW,

Harold
 

·
Senior Contributor
Joined
·
4,914 Posts
A week from now I will drive to OctOpelfest, another 1200 miles round trip at much slower speed than on the video.
As long as the weather is good I will be at Octopelfest for Saturday only. Hope to see you there. Right now the weather looks cloudy Sat and sunny on Sunday.
 

·
Über Genius
Joined
·
8,828 Posts
P.S. Just received an email from local buddy: Just posting it on Youtube may be enough to get you convicted. Opel GTs are not that common and you are developing a reputation.

Should I remove the video?
Your buddy is one of "those guys".
Should you remove the video? Probably not. Unless there's a posted street sign in the video then there would have to be an investigation into where you were. The police would also have to prove a few other things.
If you are being a menace to the neighborhood, or society, then they'd investigate but for a simple ticket? Nope. There's much easier targets for revenue generation.
 

·
Registered
Joined
·
1,683 Posts
On the subject of PJ's engine running rich, the concern I had with my little 2L was that it mite be running too lean.
So in the spirit of tuning I bought a set of 150, and 155 main jets. (currently 145s) . Wasn't sure witch one to try first so I figure 155 would either really help or really suck so I tried them.

Well my first ride proved I was on the right track with the 145s. My engine became lazy and sluggish. Accelerating was noticibly slower. Idling got lower and rougher. I could no longer accelerate up certain hills on the highway in fourth gear.Where as before I would hit the throttle and the car would have pulled.

So got back home and quickly changed my mains jets back to 145, and hoped the difference in performance was not caused by something else. Thankfully the jets change did the trick and the engine performance returned to its normal strong reving, smooth idling, and satisfying acceleration I had grown to love about my engine.

That being said, I'm still surprised the difference bigger mains did. .Atleast now I know for sure, richer jetting is not required for my application. When ever my car gets dynoed I'll probably try it with 145, 140, and 135 mains jets.
 

·
Opel Intern
Joined
·
1,290 Posts
On the subject of PJ's engine running rich, the concern I had with my little 2L was that it mite be running too lean...
That being said, I'm still surprised the difference bigger mains did. .Atleast now I know for sure, richer jetting is not required for my application. When ever my car gets dynoed I'll probably try it with 145, 140, and 135 mains jets.
If the money isn't really an issue, I would highly suggest adding a wideband O2 sensor to your car - at least just temporarily for tuning purposes. If you are taking it to get professionally dynoed, then it might not be as big of a draw.

Adding an O2 sensor lets just about anyone know if they are on the right track with the changes they are making to their carb by providing a real number to check against your jet guess.

I personally used my AFR sensor to tell me when it really was time to change the jets in my carb as I drove from sea level up to 13,000 feet and back a little over a year ago. Since then it is comforting to see the car lean out as it warms up, watch the afr dip as I punch it etc. One more data point and fancy looking gauge to watch on the dashboard.

And hey, a set of main jets for a pair of DCOEs costs ~$25. Buy 10 sets of jets for tuning your carb and you have just paid for the AFR gauge!
 
41 - 60 of 63 Posts
Top