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We've been working on the intake side of things on the GT4/Spyder and using the same science that gave you the 4th runner on our headers, we improved the intake runners.
We set a goal early on for a 400whp GT4 with more torque, smoother power band and we didn't want to open up the engine to do it. So we had to find all of the inefficiencies, change how the pressure waves were timed and change the way pressure is built in the manifold.
Many versions were tested and compared to our mathematical model and we refined from there.
Prototype Version of the Intake Runners:
The final result is below:
Dundon D4 Kit: 401 WHP GT4 Stock Engine Bottom Line is GT4 Stock, Middle Line is the D2 Kit (Race Headers/Pro Tune), Top is D4 (Headers, Intake Runner Kit, CarreraS Center Plenum and TB, GT3 Muffler Kit, Pro Tune)
Summary of Gains over stock
Peak Torque gains of 40lbft at the wheels
Max Torque gains of 73lbft at the wheels
Peak HP Gains >60whp
>75whp gains at 5000rpm
>85whp gains at 7000rpm
100whp gains at the rev limiter
Maintains >300lbft at the wheels from 4000rpm to 7000rpm
Carries 380whp to redline
Here's another one that might put it better into context.
D4 GT4 compared to a 991.1 GT3 Dundon D4 Kit compared to 991.1 GT3 Stock
Since everyone will have different amounts of mods, just contact us and we'll get a package price together for you.
Those with existing Dundon Pro Tunes get a free retune
Those with IPD Plenums don't need the Carrera S Center Plenum
Those with GT3 Muffler kits don't need our kit (unless you want the cats).
Bear with us as we update the website with all the current information and Dyno's. As we fill out more of the information on the combinations I'll update here and on the website.
Last edited by Jamie@dundonmotorsports; 05-01-2019 at 03:28 PM.
These are just awesome "bolt-ons" for the GT4 & real game changers! I mean the comparison data with a stock 991.1 GT3 really demonstrates you & your team have done some amazing work! Just in time for Xmas too : )
The 981 are great cars & you guys have taken them to the next level. Even if the new model has a bump in HP, it's not going to be GT3 level, like this is.
These are just awesome "bolt-ons" for the GT4 & real game changers! I mean the comparison data with a stock 991.1 GT3 really demonstrates you & your team have done some amazing work! Just in time for Xmas too : )
The 981 are great cars & you guys have taken them to the next level. Even if the new model has a bump in HP, it's not going to be GT3 level, like this is.
Sending you a pm.
Thabk you, the comparison dynos are key. Otherwise it’s just squiggly lines. The comparison of before and after is good, but putting some stock cars on there is good as well. I’ll post this package compared to a 991.2 GT3 in a bit
this is outright amazing work. kudos have never been more deserved!
i wonder though, i would have guessed that the intake/exhaust and cams are all tuned to work together as a package, from the factory. there's always a weak link and improvements have the "side effect" of shifting the weak link to another component. for safety systems, we don't do that -- the next weaker link may not have been designed to fail "safe". i totally get it, combined intake and exhaust allows the engine to breathe better, but i'm surprised so much "room" is available for improvement in the existing OEM cam design. jamie, can you comment?
and ... are updated cams in the works next ??? i don't have an appreciation for how much tuning work would be involved or if it's possible with a cobb or similar device.
this is outright amazing work. kudos have never been more deserved!
i wonder though, i would have guessed that the intake/exhaust and cams are all tuned to work together as a package, from the factory. there's always a weak link and improvements have the "side effect" of shifting the weak link to another component. for safety systems, we don't do that -- the next weaker link may not have been designed to fail "safe". i totally get it, combined intake and exhaust allows the engine to breathe better, but i'm surprised so much "room" is available for improvement in the existing OEM cam design. jamie, can you comment?
and ... are updated cams in the works next ??? i don't have an appreciation for how much tuning work would be involved or if it's possible with a cobb or similar device.
What we’re doing is akin to adding a small supercharger or turbo charger to the engine, but we’re using suction waves on the exhaust side and pressure waves on the intake side. The OEM has a lot of considerations when making an engine, most of them cost. So were the systems designed to work together. Likely yes. But with different constraints. We opened up the performance constraints and helped the engine to have a higher volumetric efficiency. There is never “room” the OEM leaves behind to find. You must create it...
A full 4.1 and 4.5L are up next and cam and head work are apart of that. Cams will be quite expensive as you must start with factory cams. Then regrind them and DLC coat them. The cams in the GT4 are pretty mild...
When you start vastly alrering the engine model, the tuning can get tricky, but so far so good. And we have some backup in this area if needed (different maps open etc)
I would love to see what this package can do without the GT3 muffler upgrade. From the numbers it looks like it may be about ~15whp peak but surprised it makes that much difference.
Do you just need to replace the muffler? Can you keep the PSE or is this part of the restriction? I would love to keep the quite/loud modes.
I would love to see what this package can do without the GT3 muffler upgrade. From the numbers it looks like it may be about ~15whp peak but surprised it makes that much difference.
Do you just need to replace the muffler? Can you keep the PSE or is this part of the restriction? I would love to keep the quite/loud modes.
Dyno’s shown include the GT3 muffler kit. We are getting dyno’s this week with kit and PSE.
Our GT3 kit included the valves so you can toggle loud/quiet... it’s side pipes, bracketry, valves for the kit, then one of our mufflers or an OEM muffler.
Dyno’s shown include the GT3 muffler kit. We are getting dyno’s this week with kit and PSE.
Our GT3 kit included the valves so you can toggle loud/quiet... it’s side pipes, bracketry, valves for the kit, then one of our mufflers or an OEM muffler.
Thanks mate. I will wait to see what this kit can do with PSE and also wait for your GT3 muffler kit to be finished with pricing.
It will be nice if you can make a side by side video of the actual real world difference in a pull between your car and a stock GT4. That would be much more convincing. Because in the end the total package is over 10k, a comparison in addition of dyno pull would be nice.
It will be nice if you can make a side by side video of the actual real world difference in a pull between your car and a stock GT4. That would be much more convincing. Because in the end the total package is over 10k, a comparison in addition of dyno pull would be nice.
We run all of our cars on the dyno to allow for cross platform comparisons in a safe way, hence the 991.1 GT3 comparison.
That said when it's not pouring down raining here in the NW, or 35*F and we can schedule a closed airport to do the testing with a stock GT4 owner willing to run it side by side on a bumpy airport, we'll be happy to do it.
I don't condone street racing and honestly at the speeds these cars can attain, no one should be pushing 3rd gear at the rev limiter unless you're on a track.
The reason we use our dyno to show this is it's human error and environment immune.
There will be a few D4 GT4's around come spring time to go play with I'm sure...
Jamie - what type of material are the runners made from? They appear cast aluminum, is that correct?
i think I put it in the original post, but will go back and add if I didn’t. They are PA12 Nylon, just like the factory parts.
we didn’t want to cast them for heat soak reasons
Since it is hard to get a gauge of the level of improvement in the car here are a few comparisons for you to take a look at.
First up is a 997.2 GT3RS compared with the D4 GT4
D4 GT4 compared to 997.2 GT3RS with center muffler bypass Dundon Damper and Tune.
Next is a 991.1 RS compared with a D4 GT4
D4 GT4 compared to a stock 991.1RS
The intake runners are released to mfg today, we did some street tuning on the car, and to get the entire package to market faster in discussions with the gracious folks at IPD, getting our own custom silicone and breather bits ready in time would unduly delay the rollout.
Side pipes for the GT3 muffler will come off the car tomorrow as we test the PSE with the current configuration and build a tune for it as well!
I'll be updating the website with the new parts and options/combos with Dyno's for them as appropriate!
12-15-2018, 03:38 PM
Dundon Intake Runner Introduction, 401whp GT4
i don't have an appreciation for how much tuning work would be involved or if it's possible with a cobb or similar device.
