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EURO 924 NA HEAD MODS
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morghen  



Joined: 21 Jan 2005
Posts: 8177
Location: Romania

PostPosted: Sat Jan 21, 2006 7:09 pm    Post subject: EURO 924 NA HEAD MODS Reply with quote

This is to be a thread only about head modifications.
I want to learn how to mod my NA head and i want others to learn too.

first:

i am interested in how much i can oversize the head ports of the NA before i start loosing HP...whats the optimum size?

by now i know this:

1. 3 angle valve job (yea but anyone got exact mesurements ? what do i tell the machinist to do ?)

2. grinding the tight angles in the port...ok that i think it can be done in any way...just to clear the way for the air and smooth the those angles.

3. oversizing the exhaust ports(yea but by how much ?)

For all this i bought a K&N filter and i am going to get a big bore TB.
But.....anyone got numbers on those machine jobs ?
And no the machinist dosent know what to do...he just machines.
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Ruby-sh 924
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endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Sun Jan 22, 2006 3:57 am    Post subject: Reply with quote

If you tak a look at smoothies links in the "Intake valve size in relation to port size" thread, you will see a picture of my sectioned head. Study it. About all you can do is smooth the transition points. You can't straighten anything out. Also that pocket on the back wall is a deal breaker.

With that said, you may also consider back cutting the valves with a 30 cut.

Todd
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morghen  



Joined: 21 Jan 2005
Posts: 8177
Location: Romania

PostPosted: Thu Jan 26, 2006 7:29 am    Post subject: Reply with quote

i figured there is no actual reason to keep the NA head and modify it...the best way to improve performance(not including turbo) would be a 931 head with 11:1 CR pistons a 931 intake and a custom exhaust.

my question is: would that engine run without detonation ? or one with such mods need a programable ignition system and EFI ?

i think that these two changes are necesary...i put togheder today a price...over 1700 EUR thats over 2000 US for this powerd NA..my guess would be 160 HP maby more but...hey what the hell you can get that and evem more for a lot less.

and as much as i love the sound of the NA hurling when rev-ing....i think in the summer when i have the money i'll just buy an 1982 euro 931 engine or maby a whole trashed car and do an engine swap.
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Min  



Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada

PostPosted: Thu Jan 26, 2006 9:17 am    Post subject: Reply with quote

morghen wrote:

my question is: would that engine run without detonation ? or one with such mods need a programable ignition system and EFI ?

i think that these two changes are necesary...i put togheder today a price...over 1700 EUR thats over 2000 US for this powerd NA..my guess would be 160 HP maby more but...hey what the hell you can get that and evem more for a lot less.


Wha? ... Megasquirt v3.0 with megasquirt II 250 dollars us, full edis4 system that the msII can run, 100us ..... 2000us seems a bit wild.

Min
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Khal  



Joined: 26 Sep 2003
Posts: 4864
Location: Sunny and lovely interior BC, Canada

PostPosted: Thu Jan 26, 2006 11:50 am    Post subject: Reply with quote

morghen wrote:
i figured there is no actual reason to keep the NA head and modify it...the best way to improve performance(not including turbo) would be a 931 head with 11:1 CR pistons a 931 intake and a custom exhaust.

my question is: would that engine run without detonation ? or one with such mods need a programable ignition system and EFI ?


Why on earth would you need 11:1 compression?! Did someone tell you that's a good number?

morghen wrote:
i'll just buy an 1982 euro 931 engine or maby a whole trashed car and do an engine swap.


A straight engine swap from a Turbo may not be worth it. Remember, when the Turbo was made it was given a larger clutch, larger torque tube, and stronger gearbox internals, among other things... You might only succeed in trashing your driveline.
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morghen  



Joined: 21 Jan 2005
Posts: 8177
Location: Romania

PostPosted: Thu Jan 26, 2006 5:37 pm    Post subject: Reply with quote

we are talking about an 83 euro NA.

1500 is for the 11:1 pistons, head, head gasket and EFI+Ignition
the rest for the mechanic testing and small stuff.

well higher CR = faster and Je-pistons make 11:1 pistons for the 924(at least this is what i heard)

If i were to find a 931 engine i'd buy it with the clutch atatched and tyorgue tube, i know the 931 could rip the NA driveline and would defenetly torn the clutch apart.

the gearbox will hold tho...i have a 944S with a 924 gearbox mounted...the head is trashed but i think the car ran with the 924 box
its been mounted there when i bought the car for parts.

By now i let go of the ideea of tuning the engine on this car....i only need to get the money to buy a trashed 931 that still has its engine and driveline in good condition.
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ESC944  



Joined: 21 May 2004
Posts: 747
Location: FL

PostPosted: Sun Jan 29, 2006 11:42 am    Post subject: Reply with quote

Why a 931 head, you can just modify the 924 head, also why Naturally Aspirated POWER?


But hey its your motor and here are some links and bits of info about what you can expect, least its what has been done in the past. Should give you and idea, the articles even talk about valve size, cam profile, etc..


First of all... Power with the NA head has been done and proven:
http://www.geocities.com/the_924_site/Fogtown.htm
FOG TOWN ROCKET:
2.4 Liter Stroker, 924 NA Head, CIS, 7.3:1 Pistons, BAE TURBO

Quote:
His engine development program has turned the soft 100-hp four into a 270-hp bruiser at 7000 rpm on the dyno. On the street, its increased power can rocket the coupe from 0 to 60 in five seconds flat with a top speed well over 150 mph


Naturally Aspirated Power Two Example with and without the Turbo head:
http://www.geocities.com/the_924_site/Heavy1.html

HEAVY BREATHER:
Dual SOLEX Carbs, EURORACE BIG VALVE 924 NA HEAD, 98mm Crank, 9.5:1, 88.5 Pistons, GTI RODS, VARIABLE CAM GEAR


Quote:
We did not get a chance to dyno-test a Eurorace 924 Motor (Les guesses they put out over 150 hp), but we did road test one. When 60 mph came up in 7.4 sec. from a dead stop, we were convinced. "My goal was to make the characteristics of the motor more Porsche-like" says Les.


Power with the 931 HEAD on a 924 BLOCK:
http://www.geocities.com/the_924_site/IndianRed.htm

INDIAN RED:
2.3 Stroker, 88.5 Pistons, 90.5 Crank, 9.7:1, 931 head w/stock valves and 931 intake, larger injectors, 924 NA MOTOR NO BOOST:

Quote:
But performance is what its all about. And perform it does. We timed the car at 6.9 sec from 0-60 faster than just about anything around, and certainly faster than virtually any other 2.3 liter normally aspirated car. The motor screams its way to the redline, pulling strongly to 7200 rpm and above.


Last edited by ESC944 on Sun Jan 29, 2006 3:38 pm; edited 3 times in total
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ESC944  



Joined: 21 May 2004
Posts: 747
Location: FL

PostPosted: Sun Jan 29, 2006 11:48 am    Post subject: Reply with quote

EFI + BOOST with NA HEAD still = more than the 160 you want and you can crank up the boost higher...

For what you want to put into pistons.... you know you could go lower compression... more boost friendly. Just consider what has been done and documented... Even more recently Simsport is making 205HP and he isnt maxing his system out. Class spec limits his max HP.

Or install the 924 Turbo setup with EFI....

270HP... with a NA head, a after market kit and CIS? Yea I think thats a solid reciepe to follow... with EFI... you should be able to crack 300 HP easy enough.
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Khal  



Joined: 26 Sep 2003
Posts: 4864
Location: Sunny and lovely interior BC, Canada

PostPosted: Sun Jan 29, 2006 1:20 pm    Post subject: Reply with quote

ESC944 wrote:
...you should be able to crack 300 HP easy enough.


Here we go again...
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My924gtc  



Joined: 14 Aug 2004
Posts: 1362
Location: 248

PostPosted: Sun Jan 29, 2006 1:54 pm    Post subject: Reply with quote

Khal wrote:
ESC944 wrote:
...you should be able to crack 300 HP easy enough.


Here we go again...


Khal I know it would destroy the very fabric of your philosophy if everyone here who owns a 924 could make more power than your precious 931 does, but you need to face some facts.

It has been done.

It will be done again and again now that some people are making it a point to see it happen.

It can be done withn a reasonable budget if you know what you are doing.

IMHO your measly 177 factory hp 931 is nothing to brag about, and frankly I think you need to be banned from the threads that are related to performance and/or modifying things. You have zero ability in these areas and your input serves no purpose other than to thwart the efforts of others. If you have no experience yourself in these areas all that crap you have to say is rhetoric, not knowledge.


Do something yourself, with your own two hands, or don't play in the upgrade forum.
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'81 924 2.0L T
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Khal  



Joined: 26 Sep 2003
Posts: 4864
Location: Sunny and lovely interior BC, Canada

PostPosted: Sun Jan 29, 2006 2:11 pm    Post subject: Reply with quote

Aw c'mon, lighten up My924gtc. I was having a joke with ESC944.
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Paul  



Joined: 02 Nov 2002
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PostPosted: Sun Jan 29, 2006 2:14 pm    Post subject: Reply with quote

Yeah my mate Khal knows that the factory made a 375 HP 924 turbo!
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ESC944  



Joined: 21 May 2004
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Location: FL

PostPosted: Sun Jan 29, 2006 2:27 pm    Post subject: Reply with quote

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sequential  



Joined: 18 Nov 2005
Posts: 500
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PostPosted: Sun Jan 29, 2006 2:48 pm    Post subject: Reply with quote

Wow Esc944 , forget the boost business , i want your search engine , how do you find all that age old stuff. I remember and have copies of all those issues. Now less give some back ground , the guru behind Precison ( Greg brown ) used to do all the gtr 924 heads for holbert, etc. In the early eighties and his head flowed like crazy, all chevy racing stuff and in 1988 I was given an estimate of $6800 for the cylinder head complete with camshaft !

We know from past experience that The 931 motor will hold more than 300 bhp, As callaway used to produce in the excess off 200 and we would pump the boost up past there stock settings of .8- 1 bar. with there micro fueler and a trusty large boost valve.

The BAE kits for all intent and purposes where very disappointing to me at the time and callaway was the way to go. We had used them on VW's, BMW's, and 924's.

As a matter of fact , in 84 there was a 924 lurking around with a whipple sucking thru a 32/36 weber and was really a good runner for the time , I think 7psi , is what was reported for boost. The 931 when introduced was a bit weird as some was really fast and some kinda slow , i never really looked into this at the time but it was really obvious no 2 ran the same back in 80/81 /82 , Hmmm funny now think about it ..
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My924gtc  



Joined: 14 Aug 2004
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Location: 248

PostPosted: Sun Jan 29, 2006 2:50 pm    Post subject: Reply with quote

Khal wrote:
Aw c'mon, lighten up My924gtc. I was having a joke with ESC944.


Ya ever notice how the people that piss you off in the first place are always the ones telling you to calm down?

I don't take these cars lightly, obviously. That is what seperates me from the rest of the world. It is also why I will one day change the perception the rest of the world has of these little misfits.

I'll try harder to be more tolerant.
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'81 924 2.0L T
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Sponsor of the "2006 Battle in the Badlands"
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