HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Tim's 944LS1 track car build!

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Re: Tim's 944LS1 track car build!

Post  Rich L. on Thu Sep 11, 2014 1:41 pm

Looks great! That is pretty low but nice setup if removal is easy enough. That tow hook mount is the opposite of the new pedestrian airbags in current Euro cars. Twisted Evil
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Re: Tim's 944LS1 track car build!

Post  Lemming on Fri Sep 12, 2014 5:46 pm

Trying to get the the car loaded, think I have time for a beer break What a Face

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Re: Tim's 944LS1 track car build!

Post  Lemming on Tue Sep 16, 2014 7:39 am

Couple pics from last Saturday.

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Re: Tim's 944LS1 track car build!

Post  Lemming on Mon Sep 22, 2014 2:44 pm

First real test of the hydra boost at Barber this past weekend.  I do not like the feel of the HB as much as the DMC, but I do like the fact that I'm not having to push as hard.  I compared data from pre and post HB install and the rate of deceleration is similar between HB and DMC.  The big difference for me was that I was/am still trying to "put my faith" in the new HB system and I was tending to brake earlier.  Another issue that I had was that I had too much rear brake.  This was not a problem with the DMC, since I could adjust at both the DMC and the adjustable proportioning valve.  With the DMC I was running 3/4, 3/4 bores, the mustang MC is 1 and 1".  I may have to step down a compound in the rear (currently DTC 70/60 F/B).  I am not running the mustang proportioning valve, only have my adjustable unit in the cockpit.

PS fluid temperature was not really an issue.  Coming off track it was always right in the 200 - 206 range, regardless of run time (5 - 25 minutes).  My current PS cooler is not in a direct airstream, so I think I can drop the temps quite a bit by moving it in front of my radiator or just adding a duct.  PS pump is stock F-body type.

The only strange issue was that going into T5, I felt like I needed more brake.  I would push harder, but the pedal would not move.  I don't know if I was at the throw limit of the MC or possibly the HB unit, or that I was "out of boost" and could not push the MC in farther.  I find it hard to believe that I was out of stroke, since my DMC was only 3/4 bore with a 1.12 stroke.  The mustang unit is a 1" bore, but I cannot find the stroke length anywhere.   I'm wondering if I actually need to go back to a 3/4 bore to get higher pressure at the caliper?

Just to remind you of the calipers are Wilwood Integra 6Rs front and 951/968 rear.


Now the bad news, I lost the hydraulic slave/throwout bearing on Sunday early afternoon.  I just replaced this a few months ago!!!!!

Car was smoking pretty good, going to do a leak down test, but I'm guessing new rings and rod bearings are in order.


Last edited by Lemming on Tue Sep 23, 2014 12:42 pm; edited 1 time in total
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Mon Sep 22, 2014 10:20 pm

Lemming wrote:First real test of the hydra boost at Barber this past weekend.  I do not like the feel of the HB as much as the DMC, but I do like the fact that I'm not having to push as hard.  I compared data from pre and post HB install and the rate of deceleration is similar between HB and DMC.  The big difference for me was that I was/am still trying to "put my faith" in the new HB system and I was tending to brake earlier.  Another issue that I had was that I had too much rear brake.  This was not a problem with the DMC, since I could adjust at both the DMC and the adjustable proportioning valve.  

I’m curious if anyone has tried replacing brake lines with larger diameter (1/4”) lines on the DMC setups. The first thing I noticed on the 944 is the brake lines are tiny. In the olden days of manual brakes ,  ¼ inch lines were common.  If the line diameter is too small to flow the volume of oil required to pressurize the calipers quickly, it creates a differential pressure, pressure at the MC is higher than caliper pressure until the pressure equalizes. The result is a hard pedal and firewall flex. The 944 seems plagued with this. I plan on replacing the entire line system with ¼” and manual DMC. In regards to larger diameter lines, I’m referring to manual brakes; it would probably make HB too touchy.

Power assist is pretty much a band aid that forces more fluid through the lines than they can actually flow. That’s where brake fluid heat and brown color comes from more so than hot rotors. That’s also why your proportioning valve isn’t working as well; the power assist is pushing fluid right on by the restriction.  I don’t really like those kinds of valves, in theory, if you have enough rear brake potential, the rear brakes could lock up after the system pressure equalizes during long hard stops.

As far as T5, Could be stroke or boost system pressure too low. (I don't know a lot about HB)

Car looks good BTW!

Just an after thought, flow works both ways in a closed system. If flow is inadequate, the breaks might be dragging for a spit second coming off the turns. It won't matter unless you being timed. Wink

Edit: I have a tendency to say oil because I'm a hydraulic guy, insert "brake fluid" where applicable.

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Re: Tim's 944LS1 track car build!

Post  Lemming on Tue Sep 23, 2014 8:16 am

Keep me posted on the bigger lines, I'm not going to sell my DMC setup yet. I did call ECI hotrods about the mechanical booster (thread on brake forum), they said is it currently no being produced due to a problem with their supply chain.
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Re: Tim's 944LS1 track car build!

Post  Rich L. on Tue Sep 23, 2014 11:54 am

Very interesting stuff. Great news on the LS1 pump not heating the fluid too much. You might could address both bias and fluid volume issues by stepping down to stock rear 951 rear calipers. I believe it's the same pad size but with smaller pistons. This would reduce rear bias and reduce rear fluid volume needs. I run the stock rear turbo calipers without any issues in the rear, Bigreds up front and that's always where I overheat.

By the way, I finally ran my car yesterday with the power steering, no brake boost. With the TurnOne pump, fluid temps never reached 200. Even after a solid 1 hour of running they read at 196-198. With the LS1 pump I was pushing 220 in just 5 hot laps. Also, the boost of the steering was slightly less. Feel was light but okay. Overall the driving experience was much improved over manual steering, IMhO... Wink

Rich

p.s. Bummer about the slave cylinder and potential engine work.
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Re: Tim's 944LS1 track car build!

Post  Lemming on Tue Sep 23, 2014 12:39 pm

Rich,

I am running stock rear 951 calipers in the back.  If I put my PS cooler out into the airstream, I'm betting my temps would not go above 200o, similar to the T1 pump.  I'm < 10o warmer than your setup at the moment.
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Re: Tim's 944LS1 track car build!

Post  Rich L. on Tue Sep 23, 2014 5:19 pm

Oh, I got confused and thought you had front 951 calipers on the back. Yeah, your ps fluid temps are fine, glad to hear it.
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Tue Sep 23, 2014 10:27 pm

I’m afraid it will be a long while before I’ll be testing brakes or anything else.
An engine driven pump varies flow and possibly pressure with engine RPM. Were you diving into turn 5 at a different RPM than the rest of the braking zones?

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Re: Tim's 944LS1 track car build!

Post  Lemming on Wed Sep 24, 2014 7:12 am

T5 is a hairpin and the slowest turn at Barber and therefore likely that my RPMs are lower.  I'm planning on putting a restrictor after the HP, on what would be the PS line.  I'll simple braze a connector shut and then drill a hole as another on this board did on his car.


Decided last night to bite the bullet and will send off the heads to have them freshened up. Thinking about new pistons as well.
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Re: Tim's 944LS1 track car build!

Post  Lemming on Wed Sep 24, 2014 9:47 am

Hmmm, decisions, decisions. A friend of mine is selling the engine out of his wrecked car (he had a Howe TA2 car built after the crash). LSA engine pushing 505 to the wheels. New short block and top end rebuilt 6 months before his crash. pig
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Re: Tim's 944LS1 track car build!

Post  Lemming on Sat Sep 27, 2014 8:05 am

Pulled the heads last night, the bores look fine, will pull the pan today to evaluate the bottom end.  If all looks good, I may end up just rebuilding the engine.  There's a guy in town who used to rebuild my 968 heads, he can do my LS heads this weekend for less than $300 for both.
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Sat Sep 27, 2014 8:27 pm

Yeah, sounds like it just needs freshened up. Bearings, rings, guides......That's good news for you but somebody has to test the turbo S trans behind 500 hp! Razz

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Re: Tim's 944LS1 track car build!

Post  Lemming on Sun Sep 28, 2014 8:04 am

Yep, heads are already at the builder, will try to get the bottom end out of the car tonight, then disassemble and off to the machinist to be bored.

Edit: Block is out and on the stand. Off to a DE meeting, then back to disassemble the engine Shocked
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Re: Tim's 944LS1 track car build!

Post  Lemming on Fri Oct 03, 2014 8:27 am

Engine is back at home, still in pieces.  There were issues with the heads, one valve seal was destroyed and two seals were not sealing properly.  A few of the valve guides were also bad.  Heads are now back in tip-top shape.  

I also took the block to a machine shop, all bores were well within spec, so I just had them honed to accept new rings.  I'm still concerned with my excessive crank pressure, so I will be scrutinizing the pistons for cracks before re-using them.  

The rebuild will not have the crank pressure going back into the intake manifold, everything will be vented to atmosphere.

EDIT: bit the bullet once again and ordered new pistons. While I'm in there Rolling Eyes
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Fri Oct 03, 2014 10:46 pm

Have I mentioned I was once a professional engine builder/ASE certified engine machinist?
You’re doing exactly what I would do. Never install reconditioned heads on top of used rings as the increase in combustion temperatures will blow out already tired rings. The excessive crankcase pressure (blow-by) was likely the worn guides and the seals creating blue smoke. On race engines I usually ran the crankcase vent hoses to a tube welded into the header collector at a 45 degree angle extending to the center of the collector. It’s a very efficient evac system but usually on open header cars. I would watch doing this on very restrictive exhaust systems and it might fill the muffler with oil over time but it still would likely be more effective than ambient pressure.  The big inch race engine guys are using vacuum pumps. Just a thought.

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Re: Tim's 944LS1 track car build!

Post  Lemming on Sun Oct 05, 2014 9:39 am

racertomtom wrote: On race engines I usually ran the crankcase vent hoses to a tube welded into the header collector at a 45 degree angle extending to the center of the collector. It’s a very efficient evac system but usually on open header cars.

Sounds interesting, especially if it will either will blow flames out the exhaust Very Happy , or allow me to oil down the track to keep my competitors behind me pirat
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Sun Oct 05, 2014 9:49 am

Lemming wrote:
racertomtom wrote: On race engines I usually ran the crankcase vent hoses to a tube welded into the header collector at a 45 degree angle extending to the center of the collector. It’s a very efficient evac system but usually on open header cars.

Sounds interesting, especially if it will either will blow flames out the exhaust Very Happy , or allow me to oil down the track to keep my competitors behind me pirat

If you want to enhance that, you could put your old rings back in. Either way, it's not on your windshield! Very Happy


Last edited by racertomtom on Sun Oct 05, 2014 9:29 pm; edited 1 time in total

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Re: Tim's 944LS1 track car build!

Post  docwyte on Sun Oct 05, 2014 11:34 am

I've got two catch cans right now, plus the LS6 valley cover. That seems to be containing the vapors...

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Re: Tim's 944LS1 track car build!

Post  racertomtom on Sun Oct 05, 2014 9:48 pm

I don’t want to highjack the thread, but, I’m not a big proponent of venting crankcase pressure into the atmosphere because it simply doesn’t work very well. GM developed the PCV system in the 60s before it was an emissions regulation. While contaminating the intake charge robs HP, high crankcase pressure blows seals and gaskets. They elected to sacrifice 2-3 percent of a NEW engine’s horsepower to reduce the amount of oil leak related warranty claims they were paying that were traced back to high crankcase pressure. Granted, seals and gaskets are much better than they were but so are warranty periods. Unfortunately, using intake air vacuum worked very well, that is until the rings and exhaust guides wear and continue to diminish HP until it causes more HP robbing problems like detonation and the gooey gunk that restricts ports around the guides and stops up the catalytic converters. Not such a great idea for those of us that don’t always have a new car. Ironically, the company that started it all (GM) was plagued with cracked heads do to plugged cat converters in the 80s. What goes around comes around?

Engines that are raced compound the problem by running at high loads and high RPMs (increased pressure) most of the time. The problem with dumping it into the air is atmospheric pressure at sea level is an unconsidered 14.7 psi, which is too much, so we really need a mild source of vacuum to lower that number that doesn’t also contaminate the combustion charge.  Or, we can fix oil leaks all the time. Rear main seal in a 948? I don’t think so.

One solution is to leave it alone and be anal about keeping the engine freshened up. 10-15 HP on a 500HP engine isn’t much in a road race where handling, braking and driver skill usually prevails anyway.

Another solution is to vent a blow-by tube running down the block and into the airstream under the car. Of course that greases the track and installing a filtered reservoir restricts flow back to atmospheric pressure.

Running a vented hose to the exhaust right behind the muffler would be a more consistent vacuum that doesn’t depend on vehicle speed. Heat from the muffler will burn up the vapor, that is, until blow-by gets bad enough that the oil remains a liquid, then we’re dripping on the track again.

Vacuum pumps are very consistent when they work but you have to regulate vacuum to below around 10 inHg so the seals and gaskets don’t implode rather than blow. Engine driven pumps rob as much HP as the contaminated air charge and electric pumps, well; they’re the ones that don’t always work.

So what’s the best solution? Heck if I know. Probably keep the engine fresh enough that blow-by isn’t much of an issue, and then do whatever you want. I’m starting to remember why racing is expensive.Shocked

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Re: Tim's 944LS1 track car build!

Post  Lemming on Mon Oct 06, 2014 12:45 pm

Let's hope that the rebuilt engine has less crank pressure than the last, I don't really want to invest in a vacuum pump.

The remainder of the engine parts will be here today, will begin the rebuild tonight. Better make a beer run pirat
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Re: Tim's 944LS1 track car build!

Post  racertomtom on Mon Oct 06, 2014 4:28 pm

I reccomend 30 packs. Twisted Evil

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Re: Tim's 944LS1 track car build!

Post  Lemming on Mon Oct 06, 2014 10:12 pm

Didn't get as much done as I had hoped. Crank is in, pressed wrist pins out, put new pistons and pins on the old rods. Fire and ice make installing the pins a breeze. Tomorrow I'll start cutting the rings to fit. What ring gaps are people using?
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Re: Tim's 944LS1 track car build!

Post  Rich L. on Mon Oct 06, 2014 10:25 pm

Decent progress. Can't help on the ring gaps. Good luck on the rebuild.

On the PCV, mine is doing nicely with the same setup you had. Leaking stem seals can definitely put extra pressure in the crank case. With your redone heads, you shouldn't need to do anything different with your breather.

Rich
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