Forced induction - or not

roy928tt
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Re: Forced induction - or not

Postby roy928tt » 16 Jun 2016, 03:24

Sorry Kurt I 'hadn't caught up' on the story so far, re. engine failure, what was known / what wasn't.

You are on E85, so correctly, detonation can be absolutely ruled out.

I like where you are going with the shorter hot side on the turbo and straighter pressure side.

Cheers Roy

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Re: Forced induction - or not

Postby Midlana1 » 25 Oct 2016, 08:17

I brought up the following on a Honda site:

Because my Honda engine is turbocharged, aftermarket transmission gears were installed. The catch is that only gears 1-4 are available, leaving gears 5 and 6 as OEM. At Autoclub Speedway (a NASCAR track) we run flat-out down the front straight. Before the latest power upgrades I was running at 148 mph and now it'll be more. The issue is: how much am I risking feeding roughly twice the torque through the OEM 5-6 gears?

The answers:
I've destroyed 6th gear on my supercharged set up at part throttle because of the amount of torque I have at low rpms. I've been searching for a stronger replacement for the OEM ratios, but haven't found anything tall enough to go with my PPG gear set. For now, the power is cut back with boost by gear for the OEM gears.


And:
Andrew's smoked both 5th and 6th gear on his K20 MR2 back when it was just 550hp. Those gears are no stronger than 4th gear.


Sigh, so unless I want to spend $8K+ on a sequential box (which isn't guaranteed to be any stronger), torque will have to be reduced in the high gears. Just another consequence of building an engine into something it wasn't intended to be.

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Re: Forced induction - or not

Postby dpkilty » 25 Oct 2016, 08:44

Have you looked into cryogenic treating the gears themselves? It may not be a bad option...

https://www.cryogenictreatmentdatabase.org/tag/gears/

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Re: Forced induction - or not

Postby Midlana1 » 25 Oct 2016, 09:23

I haven't done any in-depth reading on whether there are test results showing it really works. The last time I looked into it, the industry's claim seemed to be that "you can't prove that it doesn't work." It's hard to know because how people treat the gears is so darn subjective, without strict double-blinded testing it's too subjective. So... no I haven't :?

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Re: Forced induction - or not

Postby dpkilty » 25 Oct 2016, 10:47

I've not done a lot of research either but I am looking into it as a service to offer for my company. Obviously I would be sending the parts to someplace that has been doing it for a while and has all the proper equipment and such.

That being said I have read a few things that put it pretty well.. Basically they said cryo treating doesn't make the part any harder, it simply makes it more wear resistant. I know I have seen multiple companies and race teams that swear by it for their gears.

That being said its not terribly expensive to treat the gears, but if you aren't comfortable removing and installing them yourself you will be paying a fair amount in transmission work to try it.

Plus the link has a lot of patent info and scientific research, not just 3rd party advertising and "testing".

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Re: Forced induction - or not

Postby dpkilty » 03 Oct 2017, 09:33

I didn't want to muddy a build thread with off-topic talk so I copied this over to here...

Midlana1 wrote:FWIW, while I'm still a fan of the Honda K-series for the street and NA track use, I can't recommend it for turbocharged usage due to the amount of work and $$$$$ to make it reliable (yes, that's 5 dollar signs...). Just as annoying, since there are no aftermarket gears for 5th and 6th, the stock gears are at serious risk of grenading at high speed (assuming the car's run on tracks where >140mph is possible). Reason for this post is to say that if your engine has a proven strong gearbox, that's worth a lot on its own, NA or not.



By no means am I disagreeing with anything you are saying here, I just want to add my 2 cents worth for the sake of discussion.

The problems you had with the K-Series blowing up isn't much different than if you would have started with a turbocharged motor from the beginning. I see countless guys blowing up their Subaru's, Evo's, and more recently Ford ST's. It's not so much a problem with the motor as much as you are pushing a motor designed to make X amount of power and you are making more.
"But the motor was built to handle 700 and blew up at 400..."
I can't say why it happened. I don't know, from what I have seen it sounds like it's possible there was a knock event for whatever reason. I don't want to rehash all that as speculation is all it will be on our end.
If you want reliability then stick with a stock motor on stock power levels. That is really the only way to get reliability.
To say the K-series isn't a good candidate for boost is a little unfair to it. Yeah, you need to spend $$$$$ to make double or triple the hp in a somewhat reliable setup, but that isn't really any different than any other platform. For example, if I want to try to make 500 hp from a 2.5L Subaru EJ motor I am going to be spending at least $4500 or more. That's a minimum and likely wouldn't last long. To do it right you could double that price. Even then you aren't guaranteed reliability...
Each platform has its pro's and cons for sure. No arguments there.

Maybe one way to look at it is in a similar way that you did at the braking system.
Do we really need all that power? The car weighs 1/2 as much as the donor car (if not more). So a 225hp engine in a 3000-pound car is going to act far differently than a 225hp engine in a 1500-pound car. Even if it's exactly the same engine. The power loads the suspension differently and the reduced weight acts much differently. I know a Lotus Elise with a K-series motor has to be tuned differently than a Honda Civic with a K-series for the reasons stated above.

As for the gearbox.... Good luck. Finding high hp capable gearsets in FWD isn't easy on any platform. Subaru 5 speeds are time bombs once you hit 350 or so. Aftermarket support is a big player here. If there is a lot of support for the gearbox then your better off than not obviously.

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Re: Forced induction - or not

Postby Midlana1 » 03 Oct 2017, 13:40

I mostly agree; I'm seeing things through the lens of a Honda K-series engine. The only thing I disagree with is that the desired power / stock power is going to be different for an NA versus a factory turbo engine. For example, I started with a NA engine which was around 170 hp and wound it up to ~450 hp, so that's 450 / 170 = 2.65 time the power. Now had I started with (for the sake of argument) a 300-hp Subaru STi engine and wound it up to the same 450 hp, that's a factor of 450/300 = 1.5. My point is that the desired hp has to be factored it and for any reasonable (hah!) targets, starting with a factory turbo engine will "probably" result in a lot less breakage than starting with an NA engine. How much more reliable it is can only really be determined by visiting various forums and see which engines stay together well (I hear the last gen Toyota Supra engines held up fine with stock internals all the way to around 1000 hp. Just. Wow. Others, not so much.


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