5.4L Engine Build Questions
11-17-2009, 03:14 PM
#1
Man of many SIGs
Rennlist Member
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Thread Starter
5.4L Engine Build Questions
I started this thread on Reutterwerk but I'd like to mirror it here as well to get some additional feedback. http://reutterwerk.com/forums/showthread.php?t=15148
Hi guys and gals. I am in the process of building a 5.4L using custom 104mm pistons in an otherwise stock 85-86 long block. Will I need a new harmonic balancer? I'm assuming I will. Can I use the GTS harmonic balancer or do I need an aftermarket balancer? I know the GTS crank is different than previous model years. What are the differences other than the amount of counterweights?
In addition, I will be using an S4 intake and S4 heads on this engine along with the wide fire ring 951 head gaskets. I'm going to be using different pistons so don't worry about the compression #'s normally attributed to that combo. Are there any things I should know or watch out for with this combo? This will be a turbo engine if that makes a difference to you.
The heads I bought are 1R heads. Can these be drilled for the GTS cooling mod? I keep hearing that these heads are "thinner". In what way? What exactly does that mean and how might it effect my build plans?
Thanks,
.........................................
I just realized what I had written earlier. I cannot use the 951 gasket if I go to 104mm. Hmmm? Any ideas? Are the Cometic gaskets built to order? If not, does someone stock the 104mm variety?
In addition, does anyone have a pic of the S3 and S4 pistons side by side?
.....................................
Quote:
Originally Posted by ptuomov
Greg Brown could probably help you out. He's got both experience and strong opinions about what works on 928.
There was also a thread by 928MS on RL today about head gasket options, they have 104mm bore gaskets available.
The workshop manual has those, pages 13-24b and 13-24c.
I found a set of Cometics on Ebay for $179
.......................................
Quote:
Originally Posted by BrendanC
Ah, yes, the GTS snout is a different diameter. Damn! I Forgot about that.
The diameter is different. Hmm, well there goes the idea of using the GTS dampner.
Does anyone know if Mahle will make a set of custom pistons like some other manufacturers will? I found out that Dinan is using Mahle pistons with the original ferostan coating when they build their hopped up alusil BMW engines.
................................................
Quote:
Originally Posted by 928 GTS
With 104mm bore its possible to use factory 944S2/968 gasket. They need to be modified a little to work but its not bad. I don't see need for Cometics unless engine will bee boosted. 103mm or some other non Porsche piston diameter is another matter and Cometic is only easy to find solution.
It will be boosted.
Quote:
Originally Posted by backslider
I've done two of these 104mm/stock 5.0L crank builds, but used the '89/newer heads on both of them. The kind of expense (and turbo boost) you're going to in doing this build, you probably should have opted for the newer heads, 19mm thicker/thicker bosses/longer bolts. Both of my sets of heads and blocks were machined for Cometic gaskets, which added about $95 of machine cost to each motor.
How many issues have been reported with the 1R heads? I know that some people say they are weaker and could crack, but has this happened in reality? I have some S3 heads but all of the valves are either broken or bent. I found a great deal on some 1R S4 heads from PtuomoV and I thought that would be a better way to go considering they were cheaper than buying all new valves and the valves are a little bigger.
The harder I look at this project the less sure I am on it's direction. Originally I planned on using Woessner pistons that are supposed to be compatable with the alusil. This would allow me to use my stock rods. This option would require me to buy a custom dampner.Of course no one can assure me that the Woessner coating will work although the 951 guys claim they haven't had any issues.
If I use the S4 heads on my S3 long block ( retaining the stock S3 pistons )the compression ratio is going to be sky high. Around 13:1 or so from what I can tell. That isn't even feasable for a N/A engine let alone boost. So either I need to rebuild my S3 heads or change the pistons.
I would prefer forged pistons. If I use forged pistons for alusil, I would need to stick w/ the 100mm diameter. This would allow me to use 951 pistons but would then require custom rods to make up the 2mm or so difference in length. Does anyone have CC #'s for 951 pistons? Custom rods are about $1,800 or so from Pauter if I remember correctly. The pistons can be bought used for about $400 - $500. I have no idea how much new pistons would be, or if they're even available.
I have 4 968 pistons ( 104mm ) but they will also require different rods. I don't think these are forged. Can anyone confirm? Pricing would pretty much be the same as above only with the added machine and finishing cost to overbore.
I could always send the block up north for Nicasil plating but shipping an aluminum engine block halfway across the country is just asking for trouble in my opinion. This option would open up a plethora of piston options. The Nicasil is going to be about $1,200. Then the pistons would be another $1,200 or so depending on the brand.
So far, the only thing that is set in stone is that I own a 5L 85 long block, S3 heads w/ bad valves and an S4 intake. The engine management will be Megasquirt. This will be a boosted engine. Boost level to be determined by the build. Minimum of 9psi, which could feasably be done with stock internals if need be.
I'm open to any and all suggestions. Fire away.
Hi guys and gals. I am in the process of building a 5.4L using custom 104mm pistons in an otherwise stock 85-86 long block. Will I need a new harmonic balancer? I'm assuming I will. Can I use the GTS harmonic balancer or do I need an aftermarket balancer? I know the GTS crank is different than previous model years. What are the differences other than the amount of counterweights?
In addition, I will be using an S4 intake and S4 heads on this engine along with the wide fire ring 951 head gaskets. I'm going to be using different pistons so don't worry about the compression #'s normally attributed to that combo. Are there any things I should know or watch out for with this combo? This will be a turbo engine if that makes a difference to you.
The heads I bought are 1R heads. Can these be drilled for the GTS cooling mod? I keep hearing that these heads are "thinner". In what way? What exactly does that mean and how might it effect my build plans?
Thanks,
.........................................
I just realized what I had written earlier. I cannot use the 951 gasket if I go to 104mm. Hmmm? Any ideas? Are the Cometic gaskets built to order? If not, does someone stock the 104mm variety?
In addition, does anyone have a pic of the S3 and S4 pistons side by side?
.....................................
Quote:
Originally Posted by ptuomov
Greg Brown could probably help you out. He's got both experience and strong opinions about what works on 928.
There was also a thread by 928MS on RL today about head gasket options, they have 104mm bore gaskets available.
The workshop manual has those, pages 13-24b and 13-24c.
I found a set of Cometics on Ebay for $179
.......................................
Quote:
Originally Posted by BrendanC
Ah, yes, the GTS snout is a different diameter. Damn! I Forgot about that.
The diameter is different. Hmm, well there goes the idea of using the GTS dampner.
Does anyone know if Mahle will make a set of custom pistons like some other manufacturers will? I found out that Dinan is using Mahle pistons with the original ferostan coating when they build their hopped up alusil BMW engines.
................................................
Quote:
Originally Posted by 928 GTS
With 104mm bore its possible to use factory 944S2/968 gasket. They need to be modified a little to work but its not bad. I don't see need for Cometics unless engine will bee boosted. 103mm or some other non Porsche piston diameter is another matter and Cometic is only easy to find solution.
It will be boosted.
Quote:
Originally Posted by backslider
I've done two of these 104mm/stock 5.0L crank builds, but used the '89/newer heads on both of them. The kind of expense (and turbo boost) you're going to in doing this build, you probably should have opted for the newer heads, 19mm thicker/thicker bosses/longer bolts. Both of my sets of heads and blocks were machined for Cometic gaskets, which added about $95 of machine cost to each motor.
How many issues have been reported with the 1R heads? I know that some people say they are weaker and could crack, but has this happened in reality? I have some S3 heads but all of the valves are either broken or bent. I found a great deal on some 1R S4 heads from PtuomoV and I thought that would be a better way to go considering they were cheaper than buying all new valves and the valves are a little bigger.
The harder I look at this project the less sure I am on it's direction. Originally I planned on using Woessner pistons that are supposed to be compatable with the alusil. This would allow me to use my stock rods. This option would require me to buy a custom dampner.Of course no one can assure me that the Woessner coating will work although the 951 guys claim they haven't had any issues.
If I use the S4 heads on my S3 long block ( retaining the stock S3 pistons )the compression ratio is going to be sky high. Around 13:1 or so from what I can tell. That isn't even feasable for a N/A engine let alone boost. So either I need to rebuild my S3 heads or change the pistons.
I would prefer forged pistons. If I use forged pistons for alusil, I would need to stick w/ the 100mm diameter. This would allow me to use 951 pistons but would then require custom rods to make up the 2mm or so difference in length. Does anyone have CC #'s for 951 pistons? Custom rods are about $1,800 or so from Pauter if I remember correctly. The pistons can be bought used for about $400 - $500. I have no idea how much new pistons would be, or if they're even available.
I have 4 968 pistons ( 104mm ) but they will also require different rods. I don't think these are forged. Can anyone confirm? Pricing would pretty much be the same as above only with the added machine and finishing cost to overbore.
I could always send the block up north for Nicasil plating but shipping an aluminum engine block halfway across the country is just asking for trouble in my opinion. This option would open up a plethora of piston options. The Nicasil is going to be about $1,200. Then the pistons would be another $1,200 or so depending on the brand.
So far, the only thing that is set in stone is that I own a 5L 85 long block, S3 heads w/ bad valves and an S4 intake. The engine management will be Megasquirt. This will be a boosted engine. Boost level to be determined by the build. Minimum of 9psi, which could feasably be done with stock internals if need be.
I'm open to any and all suggestions. Fire away.
11-17-2009, 04:30 PM
#2
Nordschleife Master
I bought an ATi damper, plan on used 968 pistons, bored and lapped 85/86 block, and modestly ported/cleaned up Euro S2 heads, with a webcams welded hotter than S grind. Good chance I will try some improved intake ideas. Once I know where that combo takes me, I may have some more things to try. Once I have all the parts in hand, I may run the info past ATi to see if I need to change rubber bands, but the dampener isn't special for balance, its to absorb torsional harmonics in the crank. Seems to me something that should be measured, not calculated.
If you want to build a wicked boost motor, why not start from a low compression S4 short block and S3 heads?
If you want to build a wicked boost motor, why not start from a low compression S4 short block and S3 heads?
11-17-2009, 07:34 PM
#3
Man of many SIGs
Rennlist Member
Rennlist Member
Thread Starter
I bought an ATi damper, plan on used 968 pistons, bored and lapped 85/86 block, and modestly ported/cleaned up Euro S2 heads, with a webcams welded hotter than S grind. Good chance I will try some improved intake ideas. Once I know where that combo takes me, I may have some more things to try. Once I have all the parts in hand, I may run the info past ATi to see if I need to change rubber bands, but the dampener isn't special for balance, its to absorb torsional harmonics in the crank. Seems to me something that should be measured, not calculated.
If you want to build a wicked boost motor, why not start from a low compression S4 short block and S3 heads?
If you want to build a wicked boost motor, why not start from a low compression S4 short block and S3 heads?
11-17-2009, 10:13 PM
#4
Man of many SIGs
Rennlist Member
Rennlist Member
Thread Starter
I bought an ATi damper, plan on used 968 pistons, bored and lapped 85/86 block, and modestly ported/cleaned up Euro S2 heads, with a webcams welded hotter than S grind. Good chance I will try some improved intake ideas. Once I know where that combo takes me, I may have some more things to try. Once I have all the parts in hand, I may run the info past ATi to see if I need to change rubber bands, but the dampener isn't special for balance, its to absorb torsional harmonics in the crank. Seems to me something that should be measured, not calculated.
Do you know if these pistons are forged? I have heard both yes and no.
