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Winter Race Car Projects
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Sun Jan 17, 2021 1:14 am    Post subject: Winter Race Car Projects Reply with quote

A log of upgrade projects for the race car.

First I'm starting on building a new motor using the 941 head in a NA application. I bought a cam from the Netherlands, CatCam. It is a 294 duration,248@.050. A typical full race duration would be about 310, but then the power range gets much tighter and with a standard gearbox (and not that good a driver) would probably be a disaster. Power range on the cam is 3000-7000. I'm using Ferrera 7mm stem valves with 36mm exhaust and a huge intake(2"+) that needs cut down to 40mm. I got the 2208P valve because it is cut back at 12 degree rather than the standard 20 and which is supposed to help quite a bit with the type of port the head has. The price of valves has goe up significantly and the blanks are almost $40 each. I'll be using PAC racing ovate beehive springs for the 4.6l Ford motor as physically they work well. Springs are the 1214X with a closed seat pressure of 120lb. Several local motor builders recommended that for a race type motor. I weighed the stock setup vs the new and stock valve train is about 216gm(less spring) and new with a Parner solid lifter will be closer to 130gm. Significantly less load on the cam and drive setup. I got an adjustable cam gear with the cam.

I had hoped to have Ferrera cut the valves to length and maching for the Ford locks, but Covid stopped that. The machinist is finding some much easier to machine single ring locks rather than the triple ring Ford ones.

I worked at porting the head, exhausts got polished only I got the intakes improved by about 8% over the stock version by smoothing the short radius curve. I a sectioned NA head and the port walls are not that thick so I was unwilling to go too far enlarging squaring the port. Ideally the short raidus curve would be filled and lengthened and then the sides enlarged to keep the volume correct, but that is well beyond my skills.

I can't really compare the NA head to the 931 head as my testing method changed dramatically using a real block rather than a bored out wood block as the base. The 931 head does continue to improve a higher lifts where the NA head stall out at .400 lift. Hopefully some pictures get attached

https://imgur.com/Z9y4aL9
https://imgur.com/jWJxQM3
https://imgur.com/IXIurAm

It will probably take another couple of months to get completely assembled, I'll retest it then.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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Juho  



Joined: 03 Oct 2018
Posts: 377
Location: Finland

PostPosted: Sun Jan 17, 2021 1:36 am    Post subject: Reply with quote

What pistons are you going to be running?
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Sun Jan 17, 2021 2:37 am    Post subject: Reply with quote

I'll get JE with somewhere around 11.5+- compression. When I talked to EBS Racing they said "Oh, I remember getting those pistons' so I'll go that way. This is not a low budget motor, I already have over quite a bit in parts for the head includes valves, springs retainers, lash caps, lifters, cam.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1353
Location: Washington DC area

PostPosted: Sun Jan 17, 2021 4:04 am    Post subject: Reply with quote

Mike,
That sounds like an awesome engine. What series/class do you plan on running?
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Sun Jan 17, 2021 4:57 am    Post subject: Reply with quote

We have vintage racing that are supposedly built to old specs. Mine are the 1981 SCCA Dp which was really pro racing at the time. Some of the cars are built to 1972 and others to 1965 standards, we all run together. One time we had a 1953 MGTD that had run the PanAmericana once and an old Allard comes out a couple of times per year. Most peoples motors are built with more modern materials and components. How many people in 1968 had dry sumped MGB's and the now common Accumsumps hadn't been invented yet. In reality it makes for much more reliable motors.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1353
Location: Washington DC area

PostPosted: Sun Jan 17, 2021 7:33 am    Post subject: Reply with quote

Ah, yes. I raced in SCCA's D-Prod ('69 911 Targa) in the '80s. I went to the Runoffs in Atlanta and watched the D-Prod 924s kick butt. SCCA gave them the 931 head, Kugelfisher injection, dry-sump and discs around. Probably the last time that Porsche gave money to SCCA Inc in trade for some 924 NA "allowances". In the mid-eighties Porsche went away from the club and the D-Prod 924s filtered down to more local races.
Dan/Ideola knows a lot about the 16 or so D-Prod 924s that were built. I raced against a few in Nationals at the time. It only took me another 25 years to realize what a great tub it was and I finally made the decision to build one (then another) after seeing Vaughan Scott's video of his efforts at the Regional Runoffs at Road Atlanta. By that time, all the original D-Prod 924s were parked and SCCA classified the 924 without all the goodies in Improved Touring B (mostly stock everything except suspension and exhaust). Good times.
With a built engine you should have a good time in Vintage.
+1 on AccuSumps. I've never lost a bearing on any of my engines (BMW, Benz, 924s) after starting to use them around 1997.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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924RACR  



Joined: 29 Jul 2001
Posts: 8794
Location: Royal Oak, MI, USA

PostPosted: Sun Jan 17, 2021 10:50 am    Post subject: Reply with quote

Fifty50Plus wrote:

+1 on AccuSumps. I've never lost a bearing on any of my engines (BMW, Benz, 924s) after starting to use them around 1997.


+Juan to this! Definitely key to keeping the 2.0L happy; that and a big oil cooler.
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'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
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emoore924  



Joined: 13 Apr 2004
Posts: 2815

PostPosted: Mon Jan 18, 2021 3:19 am    Post subject: Reply with quote

Many of the DP 924s were cut up and converted to GT3 spec as the rules changed back in about 83 or 84. They were just old race cars at the time. Because of this, there are not many if any of the "original" 16 DP cars remaining in as-raced DP configuration, unless they were returned with a more modern restoration. There was a rumored 17th car, an unbuilt car, that I had been trying to track down many years ago but I didn't get past the "pictures" stage before it was sold and the trail went cold. I still have the pics someplace but that's a story for another day...
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Harm  



Joined: 02 Apr 2009
Posts: 1373
Location: Holland

PostPosted: Mon Jan 18, 2021 7:43 am    Post subject: Reply with quote

emoore924 wrote:
…There was a rumored 17th car, an unbuilt car, that I had been trying to track down many years ago but I didn't get past the "pictures" stage before it was sold and the trail went cold. I still have the pics someplace but that's a story for another day...

You mean like one of those out of Vasek Polak's warehouse?
https://rennlist.com/forums/924-931-944-951-968-forum/967398-post-a-picture-of-a-race-car-water-cooled-front-engined-porsche-4.html#post13857544
(You know …he also stashed a GTR in there!?!)

Back to OT.
Cheers.
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emoore924  



Joined: 13 Apr 2004
Posts: 2815

PostPosted: Tue Jan 19, 2021 5:25 am    Post subject: Reply with quote

Kind of like that. But VPs car was #14 of 16 IIRC. The car I was chasing was actully a #17, which wasn't supposed to exist,...
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Mike9311  



Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish

PostPosted: Thu Jan 21, 2021 12:22 am    Post subject: Re: Winter Race Car Projects Reply with quote

MikeJinCO wrote:
A log of upgrade projects for the race car.

First I'm starting on building a new motor using the 941 head in a NA application. I bought a cam from the Netherlands, CatCam. It is a 294 duration,248@.050. A typical full race duration would be about 310, but then the power range gets much tighter and with a standard gearbox (and not that good a driver) would probably be a disaster. Power range on the cam is 3000-7000. I'm using Ferrera 7mm stem valves with 36mm exhaust and a huge intake(2"+) that needs cut down to 40mm. I got the 2208P valve because it is cut back at 12 degree rather than the standard 20 and which is supposed to help quite a bit with the type of port the head has. The price of valves has goe up significantly and the blanks are almost $40 each. I'll be using PAC racing ovate beehive springs for the 4.6l Ford motor as physically they work well. Springs are the 1214X with a closed seat pressure of 120lb. Several local motor builders recommended that for a race type motor. I weighed the stock setup vs the new and stock valve train is about 216gm(less spring) and new with a Parner solid lifter will be closer to 130gm. Significantly less load on the cam and drive setup. I got an adjustable cam gear with the cam.

I had hoped to have Ferrera cut the valves to length and maching for the Ford locks, but Covid stopped that. The machinist is finding some much easier to machine single ring locks rather than the triple ring Ford ones.

I worked at porting the head, exhausts got polished only I got the intakes improved by about 8% over the stock version by smoothing the short radius curve. I a sectioned NA head and the port walls are not that thick so I was unwilling to go too far enlarging squaring the port. Ideally the short raidus curve would be filled and lengthened and then the sides enlarged to keep the volume correct, but that is well beyond my skills.

I can't really compare the NA head to the 931 head as my testing method changed dramatically using a real block rather than a bored out wood block as the base. The 931 head does continue to improve a higher lifts where the NA head stall out at .400 lift. Hopefully some pictures get attached

https://imgur.com/Z9y4aL9
https://imgur.com/jWJxQM3
https://imgur.com/IXIurAm

It will probably take another couple of months to get completely assembled, I'll retest it then.


Mike this is awesome... I'm working on a somewhat similar setup only in that I am using the Ferrea valves (similar to Gegge) for a turbo motor. Quick question: Is your machinist cutting the single groove in the hardened section of the tip or does the setup geometry not lend itself to that location? Everything I've seen shows a groove in the hardened section but I am still wondering

My 1st spring choice will be different than the PAC setup though since I am capitalizing on the weight savings which allows for me to play with the spring choice. I have the PAC choice in the wait list though

Really interested to see how your motor runs and hope for vids with audio!!!
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Thu Jan 21, 2021 3:53 am    Post subject: Reply with quote

I have Ferrera blanks which are unhardened. Exhaust is F0034,36mm and intake is F2008P which is over 2" so needs cut down. The F1418 is a 20 degree, 40mm intake and was my obvious initial choice. Both valves are well too long, about 145mm. So cutting down length is required. I measured the clearance from the cam to the top of the Parner follower with the stock 133mm valve at about 0.165". So I using a RD Spring 7mmx.085 lash cap and then I'll use a 9mm Alfa lash cap on top of that for clearance. Yes a bit cluggey, but we have one surface grinder in the county if any adjustment is needed. Alfa caps are about $6 each, I adjusted the valves in current motor including removing the distributor and cam in about 2 hours and a cost of $25.

I used the 1214X springs as a little more seat pressure than their other ones, though the rate is the same. I think the racer folks like a bit higher pressure is because at higher revs the valves do tend to bounce a couple of times when closing and the higher pressure helps that. All valve spring seem to loose about 7% after 1000 miles. For a street motor I would use ones with 80-90 lb seat pressure. When looking at the Ford stuff need to remember that the Ford 4.6 valve train is very light, 6mm or 7mm valves (and shorter)and a rocker cam follower is all.

Several people told me that at high revs a 40mm valve on a 6mm stem the valve head will flex at high revs. Only thing I do know is that when looking a modern engines with the 5 and 6mm valve stems, they tend to be 4 valve and be quite a bit smaller than our 40mm intake.

The difference is that with my street car I sometimes run it up to 4k rpm, generally stay in the 3-4k range. I the race car I really try to make sure is always over 3500in order to stay in the power range. I have a bad tendency to shift into 4th at 5k in 3rd. Revs drop to 3600, I need to shift at minimum of 5500 to stay up on the power. Due to stock rod bolts the MSD ignition cuts out at 6k. Its a different world, but then you hope the motor lasts 50-60 hours.
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'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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Mike9311  



Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish

PostPosted: Thu Jan 21, 2021 7:55 am    Post subject: Reply with quote

Mine is a street and maybe/likely 'track day' motor. I want to play to the fact that spring pressure can be lighter due to a much lighter valve train. I had my reservations about the thin stems but I know Gegge runs them and a lot of factory race teams run them this thin. I think I like the nervous energy I create for myself to push it a bit. I am building two motors though. One is simply the back up and is closer to stock if things just go all wrong

Not sure from memory what I show in this pic. One is the stock size. Plus there is a 42/38mm and a 46mm I can play with (take it to 44mm) but I was hoping to keep it as light as possible to use the lighter pressure you suggest. It isn't about high rpm with me but in your case I could see that for sure. Fun


_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Thu Jan 21, 2021 8:33 am    Post subject: Reply with quote

I initially bought a stock spring and retainer from Rock Auto to see what they looked like. The spring is sort of a beehive/conical, the retainer was heavy and didn't fit the spring well. PAC has 4 springs that fit the 4.6 and they cost about $10 from Summit racing, Crower has springs also some also. The Crower retainers are made for the PAC springs and were under $5.00 each from JEGS, the same retainers from Ferrera were $9.00 ea. The stock 931 retainer 28gm, Crower 7.7gm. The chevy folks spend a fortune on titanium retainers to save 4 or 5 gm.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
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Mike9311  



Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish

PostPosted: Thu Jan 21, 2021 9:41 am    Post subject: Reply with quote

Nice

You did the same as I did by ordering test pieces. I wish at the time I had ordered everything because the valves doubled in price

Those chevy guys want more RPM Its crazy how much more they get by going titanium but as you said, so is the price
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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View user's profile Send private message
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