924Board.org

[Rasta Monsta]

Just watched those British kids installing your kit on YouTube and it was awesome.

Like Top Gear, but without the racism!


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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Beartooth]

No racism in Top Gear (the Clarkson/May/Hammond stuff; I haven't paid attention to anything since), just enough heat to melt the snowflakes. It did get formulaic, but at its peak, it was gold.
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1980 931 diamond in the rough

[morghen]

[924-UK]

[Cedric]

[morghen]

Precisely what Cedric said.
I really looked into intercooling, and it is possible...BUT...we then no longer have a bolt on system, you're moving into cutting holes in the car body, into additional mods to the cooling system (and a process of bleeding), additional CNC machined components...basically additional complexity and cost from every point of view.

Take the added cost and complexity of an intercooler, put it against what you can gain...and have a look at the room for improvement of the fueling and ignition.

So lets say you can gain an extra 20hp and 25Nm by intercooling and running more boost, even though your fuel system and ignition cant really keep up with more boost. You'll cut into the car body, add a lot more parts, modify other systems in the car as well.
Or you can bolt-on and plug-in a modern engine management system...keep the low boost, keep the relatively reduced complexity and cost of the current system...and gain that 20hp and 25Nm as well as improved reliability...by just bolting on and plugging in some stuff.

IAT is not that high on this setup even on a hot summer day, when choosing the compressor i studied its efficiency map and plotted the used area for this application and Cedric helped with simulating the system in order to check some critical aspects and be able to define materials and details of components. Obviously the complete setup was balanced to use the most appropriate compressor and its most efficient sweet spot (as much as possible), with respect to the capability of the 924 fueling, ignition, engine and of course other factors like availability, added complexity..etc.

I've been running ethanol injection into the supercharger inlet and while i'm running a rudimentary on/off system triggered by pedal input..i can say that i can run decent ignition timing and floor the car even in hot summer days. The videos on my website are shot in mid August.
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https://www.the924.com

[Kenodog]

[morghen]

Thank you for the kind words, all people involved should feel proud even though we dont have much in terms of gains measurements as these cars are all kind of old and worn down.
We have some acceleration graphs and calculations based on Erik's 924(has a fairly fresh engine) and referenced to my Cayman and my own 924.
But regardless of the engine condition of any 924SC out there..we do have the noise, the oversteer, the look and the cool factor and i hope this is another reason to enjoy driving and love your 924.

All this is possible because of community support, both from technical point of view with guys like Cedric and others having critical influence either directly or indirectly and also from financial point of view....there were a hand full of first adopters which are kind and patient to nurse the maturing of a product.
So long story short we did this and we are doing this.

I'll take this opportunity to announce that we're almost out of them custom silicone boost pipes that i had tools built for and ordered a decent amount of (about 60 sets or so).
I've talked to the supplier that makes them (in Europe) and they will gladly make some more...but last time i ordered was 2022 i think...and 2024 will have different costs attached due to what is happening in the world today.
This will likely be valid for all other components that i stocked to a certain amount and running out of soon....so i'm not sure if the kit will still be relevant from financial point of view for so many people starting with next year.
We'll see what the new year brings.
But i'm thankful to all the people involved.

In regards to TopGear....to me there is only one TopGear...and i fondly remember watching that a lot with my miss back in the day. Sigh...good times.
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https://www.the924.com

[morghen]

The Car Throttle guys have put their 924 on the dyno, a bit prematurely but still a decent result with respect to what they started with (their car made just 70hp before supercharging).
They got a 40whp increase even though the supercharged run was cut short at 4400RPM due to fueling issues.
The torque is decent, around 200Nm but i think that should also be better if they fixed the fueling issue or whatever is dragging it down.
Maybe if they would have taken the measurement up to 6300RPM it would have made 140 even in the current state of their engine/k-jet but they stopped when it was leaning out and got 114hp at 4400RPM and about 200Nm at 3700.
But surely not all the gain is due to the supercharger itself, likely they improved the tuning and done some work to the car as the calculations and estimations of the kit is that it adds 20% more power/torque and their gain is more than that.

https://youtu.be/VJwzF8yU8Dg?si=H4L7jCYXJg31mf_z
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https://www.the924.com

[Riggard]

I love the series and it's cool to finally get some figures on what the kit could do. Would love to see how this progresses. Motivates me to finally install my kit too... it's been lying around for way too long already.

[morghen]

Spent about half a day on the dyno so far and at least one more round will be done.
Chased and sorted various issues but we ran out of time for the last one.
From 5000RPM upwards there seems to be a problem and the power just goes flat there.
We think it is a misfire due to bad leads but it could be something else as well, investigation ongoing (ideas welcome).

At the end of the day the partial results on an unknown mileage engine, used, worn condition but decent compression are the following:
@35hp and 55Nm gain. Aim/expectation is @45hp gain and 55Nm, i believe that once the issue above is sorted the gain will be 45hp/55Nm

One notable aspect is that it makes fairly close to max torque from 1500RPM and keeps it up to 4250RPM, and even in the very high RPM the torque only drops by @15% from maximum, so a pretty flat and wide torque curve.
These numbers dont tell the complete story, the torque curve on the SC setup makes the car very quick and capable.
There isnt an RPM or condition where it isnt pulling strong.

For the ones interested or the ones willing to share an opinion:
IAT was as high as 49C for consecutive runs, ambiend was 16C
AFR around 11.5 above 5000RPM
ignition advance: around 20deg above 5k rpm


I'll post the dyno graphs after i've sorted out the high rpm issue as i dont want partial results graphs sticking around on the internet.
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https://www.the924.com

[Riggard]

pretty awesome, especially what you say about the torque; I'm curious as to what the final graphs will look like.
Ballpark figures I've read is that per 0.1 bar boost, you should expect 10-15 hp, so those ballpark figures are not far off then, because I think the kit does 0.3bar?

Been getting quite a few questions about 'how many horsepower does it add' since I installed my kit... but the increased Torque, is what really gives you fun. HP is just a point in time (or revs). Torque determines how well it can be driven... I can confirm that it drives well, even with sub-optimal fueling (Fixed now)

As for the issue... not really sure, I've been told the old fuel pump relays have kind of a programmable rev limiter function (can be adjusted with a small potmeter), perhaps yours is a bit crooked?

[924RACR]

Hmmm, we've been plagued by slight misfire above 5000rpm on the NA racecar, basically since day 1. It tends to be tied to some accretion/build-up on the contacts in the distributor cap, presumably from the carbon button in the center, and is fine once scraped off.

But of course you've deleted all that.

Since the mileage on the motor is unknown, could it be just tired valve springs??
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Cedric]

[morghen]