924Board.org

[pcarfanatic]

Hi,

I've just had a header built for my 924 racecar. However, they have joined cylinders 1&2 and 3&4 (4into2into1). I've been told that this is wrong and that cylinders 1&4 and 2&3 should be joined, or best yet it should be 4 into 1 as i am looking for power at high revs.

Is this true and if so, any idea of how much power I am losing??? (motor has a mild 280deg cam and a gasflowed head).

Thanks

[OutOfTheBox]

yep should be 1&4 + 2&3

the links below will explain differences

http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=2

http://www.btinternet.com/%7Emezporting/exhaust_length.html

[CBass]

You're being fed misinformation. 4-2-1 is a superior design to 4-1 even for racing applications. Read some modern papers on header theory, pairing cylinders and the ability to run multiple merge collectors are big advantages.
_________________
'81 931 in various states of assembly

[OutOfTheBox]

[924RACR]

Wow, that's a whole lot of piss and vinegar and statements about how the board should be for someone relatively new.

Should I respond point-by-point with my objections to your statements? No, I think I'll pass on that, as it never leads anywhere useful. I'd encourage you to do the same. Yes, this board should be all about the open, mature, and considerate exchange of ideas.

Flaming and accusations over who's right and who's wrong does nothing to further such discussions. Life is all about shades of grey; likewise are our technical discussions, and those who fail to see this point IMO lack some maturity.

Back on topic, it's pretty clear that there are advantages to both header styles - 4-2-1 or 4-1. What may work for one engine may not work for another. My engine is very stock, relatively speaking (in spite of what you may think if you've heard it run). Therefore, with a stock cam up top, I don't think I'd ever want a 4-1 header on my engine. I'd probably lose a lot of driveability. If I were to run in a race class where I were able to do much more to the engine, including a custom cam, then I may want to look at a 4-1.

This is a legit statement from me - I've got a new MSDS 4-2-1 header on order (or, at least, I'm trying to order it... struggles communicating with the company).

This is no different than suspensions: there is no "perfect" suspension. Each such setup will be designed for a specific application, and what even works best for one driver in one situation may not be optimal for a different driver under the same considerations.

Please, let's try to be a little more open-minded here, OK?

For the record, I've been through countless head gaskets on my NA. Perhaps over 5, I've long since lost count. So, who here thinks I'm a bloody clown?? C'mon, let's hear it...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Stu2j]

[Chrenan]

OutOfTheBox, don't confuse CBass with Housebrown. CBass is a shade tree mechanic like the rest of us here, he doesn't have a hidden agenda to make a profit from anyone here, he's not using the board as his personal mall.

He is using this board as "a FORUM where IDEAS are discussed", exactly as you wished.
_________________
1987 951 - M193 Version for Japan

[Lizard]

the 924 NA engine does not produce nearly enough flow, or high RPMs to justify a 4-1 and yes a 4-2-1 would be better for your purposes.

as per Cbass's engine, he has a 931 bottom end with an NA head, this gives roughly 11:1 CR, and then the PO had ported the head, and done a bad job, this lowered port velocity which in turn leads more towards detonation, which as -nick found out, eats headgaskets. and then he ended up puking a spark plug on cyl #4 as to why he did who knows, but even Vaughan, or 924RACR has done that before.
_________________
3 928s,

[OutOfTheBox]

If I reply to a posting

[Chrenan]

[Min]

[924RACR]

Agreed, somehow we wandered off the subject of which runners should be paired for correct design in a Tri-Y.

I have to agree with Lizard, I too feel that the 2.0L just doesn't flow well enough to do much with a 4-1 (at least in anything short of a full-prep GT engine - and I don't mean Carrera GT). I recently talked with Don Istook regarding header design for the 924, who confirmed tri-Y (Martin Snyder aka MSDS, specifically, same as I've been running) as the best for my application (in the ITB car).

I also just got off the phone with Martin Snyder - actually just checking up on my order, it was lagging a little - didn't really have time to chat, unfortunately... but wanted to ask his opinion... he did have some interesting things to say about header design, but more about the 944... comparing his designs with Bursch... he used to sell the Bursch design for the 924, apparently, but started making his own - apparently a little cleaner now.

I'd still be interested in a back-to-back comparison of a 4-1 vs. a tri-Y on my car... but doubt I'll have the budget to do that kind of comparison anytime soon. Just not that high on the agenda.

As for Megasquirts, I'm very interested in doing one myself - just not that far along on the project yet...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[OutOfTheBox]

The electronics inside an ECU are basically the same from manufacturer to manfacturer, the difference between a good ECU and a bad one, will usually be in the software.

Extra features usually relate to extra electronics, so extra features doesn't mean the software is any better.

Ever had software problems on your PC, would you want the same in your car ?

But I wouldnt buy any ECU at the moment as a whole new generation are about to be developed.

Accelerometers have just dropped MASSIVELY in price.

Chip makers now have a single chip with a 3D accel' for $20.

Manufacturers are using them in the latest generation of handhelds, to tell when its been dropped, so that it switches off before it hits the ground(saves the HD). Manufacturers are also using them instead of a mouse, you wear on your wrist like a watch, and just move you hand around.

This has driven the price and size down

For those of you wondering what the hell I'm talking about, they measure acceleration, super accurately, which means they can measure the Power of your car super accurately. Which means you can make an ECU that corrects your maps realtime for maximum power.

F1 are using them but, they are still using chips that cost $500 each.

HOW MUCH ARE THEY GOING TO SELL THE STANDARD ECU'S FOR WHEN THEY BRING OUT THE NEW ONES ?

I have a couple of the new chips, which I'm going to interface with my ECU and PC.

If I had to buy an ECU tommorow I would probabaly go for a MOTEC, because they have the best all round support.

I purchased I high end unit, the manufacturers want $100 every time, they bring out new software.

[-nick]

"Since last I checked there are only 2 megasquirted(and running) 924's so far."

Ouch Min, that hurts heh heh, sigh

ps- MOTEC is great at what it does, but comparing thousands for an ECU to hundreds for a MS is hardly in the same ballpark. MS does work, quite well, and with a whole web forum of support to boot. Just my $.02 plug

Wait, weren't we talking about headers?

[Min]