View Poll Results: Pull the Holbert engine and transplant it with the 6.5 liter Rennlist engine?
Pull the engine and replace it now and start winning some races!
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31
54.39%
Run the Holbert engine 'til it blows, or run mobil 1 in it and see what happens
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3
5.26%
Replace it after this season
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17
29.82%
Sell the Holbert car on the aution TV show and put the 6.5 liter in a stock S4 race car conversion
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6
10.53%
Voters: 57. You may not vote on this poll
Should The Holbert 928 get an engine transplant mid season, or ever?
#106
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Ideally you would have adequate air and fuel and intake and valve flow, so that the engine can produce the full amount of power it can. I'm not suggesting pushing the engine beyond those areas, by supercharging or nitrous. Just to make that particular engine run as good as it can. I just fear that slapping on stock heads, stock valves, stock cams, stock intake, will be restrictive for that block. It would not take a massive amount of work to port match the heads, add larger valves, cams, sharktuning, etc. But that stuff will probably take more time than Mark has before the next race. So it won't be a problem for him, since the engine will probably run better than his old one. But it will be down on *potential* power. My concern is that he won't want to take the whole thing apart again to redo the heads and intake. So he will just keep running it with mismatched parts, and it will never run the way it could.
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Mark, you need to plan to have the heads resurfaced at the very least. Cometic gaskets may be great, but I have seen them leak after expert installation. If your heads need corrosion repair, the schedule is out the window.
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Maybe you should just use the stock stuff mark.
Any old shop will not get the surface proper for cometic. I know the engine deck is good, since Todd did it, but the heads you are in control of.
Cometic is a great gasket, but you need to have someone who is willing to use certain procedures to do it right.
Any old shop will not get the surface proper for cometic. I know the engine deck is good, since Todd did it, but the heads you are in control of.
Cometic is a great gasket, but you need to have someone who is willing to use certain procedures to do it right.
#109
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I understand the 968 stock gasket (that anderson uses) needs some modifications either on the block or gasket to work, due to the passages being slightly different. Ill have the heads re-surfaced to the tollerance needed by elsworth. they do good work and i know them, so they would probably be able to keep me on schedule.
mk
mk
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Well, you still want the engine to run without restrictions.
Ideally you would have adequate air and fuel and intake and valve flow, so that the engine can produce the full amount of power it can.
Ideally you would have adequate air and fuel and intake and valve flow, so that the engine can produce the full amount of power it can.
#111
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The head shaving machines I have seen also have a tendancy because of user error to shave the head in a sometimes crooked manner.
The concern over the ~104mm bore is that under racing conditions, a stiffer head gasket and some head studs would never hurt.
#113
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Todd does exemplary welding on the heads, and he can surface them properly as well. I don't know how much time he has right now, but he is the only one north of LA I would trust.
I can temporarily donate some very nice "head boxes" for the heads if you need to ship them. Cardboard boxes are not up to the task. My boxes are hand-made wooden "coffins"
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Andrew:
Can you get the Shrine out and dust it off? I think we're going to need it up and running for some prayer sessions at Mark's.
Can you get the Shrine out and dust it off? I think we're going to need it up and running for some prayer sessions at Mark's.
#115
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Mark mentioned doing some hand porting on the heads / intake. That is an excellent idea.......is there time to do all of this before the next race? I doubt the valve guides are in the greatest shape in the holbart motor. Is there time for a valve job as well?
Bill,
You said yourself the SharkTuner has a steep learning curve. I agree 100%, still a noob myself with the ST. Now you want to toss in the variable of a rush assembly / install with a stroker motor while still learning how to sharktune?
On a side note.....any chance you guys have a brake chassis dyno available for tuning?
Mark,
Have you figured out the external oil cooler yet? Going to tap into the same connections as the factory? That should be the easiest way. Just have new lines crimped onto the factory fittings. That is what I'm currently doing on my 79.
#116
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all i have access to is a dynojet chassis dyno. good for general safety mixture checking.
Im going to try and find a small oil cooler and mount it in front of the radiator.
modifying the existing lines will be the easy way. we have some lines with custom ends and the stock block side mounts that scot has (came with his old euro motor rebuild but were not used), so maybe he will let me fit those with new lines.(lines look old and beat up)
mk
Im going to try and find a small oil cooler and mount it in front of the radiator.
modifying the existing lines will be the easy way. we have some lines with custom ends and the stock block side mounts that scot has (came with his old euro motor rebuild but were not used), so maybe he will let me fit those with new lines.(lines look old and beat up)
mk
On a side note.....any chance you guys have a brake chassis dyno available for tuning?
Mark,
Have you figured out the external oil cooler yet? Going to tap into the same connections as the factory? That should be the easiest way. Just have new lines crimped onto the factory fittings. That is what I'm currently doing on my 79.
Mark,
Have you figured out the external oil cooler yet? Going to tap into the same connections as the factory? That should be the easiest way. Just have new lines crimped onto the factory fittings. That is what I'm currently doing on my 79.
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Sharktune? Most likely it ain't happening for this build. We are still ironing out procedural issues. We're seeing some data logging anomalies. I need to go over to the Sharktuner thread and see if they have been discussed. It's not the digi-dash issue Andrew had, but just some general MAF, AFR and RPM logging irregularities.
#118
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Do you have the Piston diameters?
I'm trying to understand the tollerances and I know you guys probably did your homework on this one.
The bore mic's out to 4.080". The ring box said 4.085" and i assume the piston diameters are 4.075. I know you say that the tops of the pistons are narrower, but i wonder by how much. I know the tollerance from JE was .004, but thats on the piston skirt. If the diameter of the piston up top is .015" narrower, then it all makes sence.
mk
I'm trying to understand the tollerances and I know you guys probably did your homework on this one.
The bore mic's out to 4.080". The ring box said 4.085" and i assume the piston diameters are 4.075. I know you say that the tops of the pistons are narrower, but i wonder by how much. I know the tollerance from JE was .004, but thats on the piston skirt. If the diameter of the piston up top is .015" narrower, then it all makes sence.
mk
I hear what you are saying and I understand your concern.
A few months ago when you brought this up I did check with all involved to verify the specs and everything was right.
You are correct in saying that the piston is typically manufactured and then the bore is finished honed accordingly to meet tolerance. A spec was given to US Chrome as was a spec given to JE and they both were verified before assembly to make sure piston to bore clearance was within the tolerance, which was dictated by JE Pistons.
A few months ago when you brought this up I did check with all involved to verify the specs and everything was right.
You are correct in saying that the piston is typically manufactured and then the bore is finished honed accordingly to meet tolerance. A spec was given to US Chrome as was a spec given to JE and they both were verified before assembly to make sure piston to bore clearance was within the tolerance, which was dictated by JE Pistons.
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Do you have the Piston diameters?
I'm trying to understand the tollerances and I know you guys probably did your homework on this one.
The bore mic's out to 4.080". The ring box said 4.085" and i assume the piston diameters are 4.075. I know you say that the tops of the pistons are narrower, but i wonder by how much. I know the tollerance from JE was .004, but thats on the piston skirt. If the diameter of the piston up top is .015" narrower, then it all makes sence.
mk
I'm trying to understand the tollerances and I know you guys probably did your homework on this one.
The bore mic's out to 4.080". The ring box said 4.085" and i assume the piston diameters are 4.075. I know you say that the tops of the pistons are narrower, but i wonder by how much. I know the tollerance from JE was .004, but thats on the piston skirt. If the diameter of the piston up top is .015" narrower, then it all makes sence.
mk
BTW, I vote keep running the engine you have in the car now. When ready, take it out and set the entire motor aside and drop in the new one. You will need to do some head and intake work to get the performance you are looking for. If you just bolt on the stock stuff the engine will make a bunch of grunt at low rpm but will fall on its face upstairs because it won't be able to breath. Look up some of the old Devek dyno sheets and you will see just what I am saying. Maybe you already have plans to do this but I have not seen you mention it anywhere.
#120
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By Danial Dudley
Fabio is correct, forged pistons are typically much looser when cold, to allow for expansion in the bores. This also means that you don't get on it until the engine is hot. Some of the stoutest engines I have ever run had sloppy pistons.
Fabio is correct, forged pistons are typically much looser when cold, to allow for expansion in the bores. This also means that you don't get on it until the engine is hot. Some of the stoutest engines I have ever run had sloppy pistons.
Let me explain why the high silicon pistons are better for most applications, this application list includes Porsche's top end current turbo models btw. Because the pistons that Porsche use are 12% silicon and are referred to as Mahle 124S, this make up of its composition is very very similar to what I use which is 4032. 4032 actually expands at a slightly more similar rate to our block material than the 124S but it is minute.
This similar expansion ratio allows the pistons to be run at a very tight clearance and as such the pistons do not slop around at all, especially if they have the offset piston pin. The 2618a pistons or Rolls Royce 58 expands quite a lot and because of this has a large clearance when cold and also requires a margin of error tolerance should the engine get hot!
That means that while you want the pistons to take up the slack when warm you need a clearance just incase you overheat the engine. Now the Nascar engine builders will not allow for that, that would cost power, due to increased friction and poor seating of the rings due to the piston not being perfectly in alignment to the bore.
Now people will say that 2618a is the best for boost, it is in general but just remember that 4032 as long as the engine is well tuned,( it can't take the knocks as well,) will be up to the task, they were even recently trialling using 4032 in the latest F1 pistons when the MMC pistons got banned, they were using 2618a before MMC came along. 4032 is good at reflecting heat to due to its high silicon content, the expansion rate doesn't change due to it being forged and the hyper eutectic pistons that are for sale cannot be forged as that material is too brittle. Hope this is of some help.
Greg