Max bore and max stroke on LS7?
01-26-2008, 07:26 AM
#21
NO Darton sleeves I know of are any .350 longer than an LS7 or you couldn't even hone them! You have an older Darton with SHORTER sleeves than an LS7 probably, maybe the 5.675 long deals but they are still longer than the oem reg LSx stuff at least which is a good thing. The Darton stuff is all awesome and I had several talks with Steve at RED about making them even longer like they are now so they could offer more skirt support down there at BDC. We did this years ago and now the Dartons are 5.800 and 5.900 long so even lower break points can be used and/or more stroke.
I mentioned after the referenced quote that I found it was the .100 shorter than the LS7, and they are supposed to be 5.900. What he told me was, mine are .350 longer than the LS2, my bad. Sorry
This is what I found after a search.
The LS2 and LS6 blocks have a sleeve length of 5.400". The LS7 has a sleeve length (to the tang) of 5.900".
I had Darton lengthen all the wet and dry sleeves to 5.800". The original designs were 5.675" which were good for 4" stroke or 4.125" stroke using a short skirt piston design. The 5.800" sleeve will accomodate 4.250" strokes.
The main problem is honing. The distance from the deck to the main bearing webs is 6.250" on all these blocks. In order to properly hone a cylinder, you need clearance (overstroke) past the bottom of the sleeve. The 5.800" Darton sleeves leave .450" overstroke for honing. Most shops will not have difficulty with this overstroke length. Another thing is you don't want the sleeve sticking out of the bottom of the block any great length unsupported. The Darton sleeves stick out .125" the LS7 .225".
The Darton sleeve is very strong so it will not spring away from the honing stones where it overhangs into the crankcase that .125". The LS7 sleeve requires a lot more effort to keep round and to size at that overhang of .225" effectively shortening the overstroke to only .350". The gray iron is about 1/3 the strength of the Darton sleeve as well which makes it even more difficult to hold size and out of round in the overhang section of the sleeve.
The C5R block is even worse in this regard. Sleeve length is 6" leaving only .250" stone over travel for honing. That combined with the gray iron liner sticking way out into the crankcase makes for a very difficult honing job.
Steve
I had Darton lengthen all the wet and dry sleeves to 5.800". The original designs were 5.675" which were good for 4" stroke or 4.125" stroke using a short skirt piston design. The 5.800" sleeve will accomodate 4.250" strokes.
The main problem is honing. The distance from the deck to the main bearing webs is 6.250" on all these blocks. In order to properly hone a cylinder, you need clearance (overstroke) past the bottom of the sleeve. The 5.800" Darton sleeves leave .450" overstroke for honing. Most shops will not have difficulty with this overstroke length. Another thing is you don't want the sleeve sticking out of the bottom of the block any great length unsupported. The Darton sleeves stick out .125" the LS7 .225".
The Darton sleeve is very strong so it will not spring away from the honing stones where it overhangs into the crankcase that .125". The LS7 sleeve requires a lot more effort to keep round and to size at that overhang of .225" effectively shortening the overstroke to only .350". The gray iron is about 1/3 the strength of the Darton sleeve as well which makes it even more difficult to hold size and out of round in the overhang section of the sleeve.
The C5R block is even worse in this regard. Sleeve length is 6" leaving only .250" stone over travel for honing. That combined with the gray iron liner sticking way out into the crankcase makes for a very difficult honing job.
Steve
01-26-2008, 10:45 AM
#22
TECH Enthusiast
iTrader: (8)
Join Date: Jul 2002
Location: old tappan n.j.
Posts: 669
Likes: 0
Received 0 Likes
on
0 Posts
I don't do that combo either since the cylinders are just not long enough. The CH is not the issue but rather the problems at BDC. I don't even do many 4.125 deals in a reg length cylinder because of this but rather mostly 4.100s or my piston gets too cramped for rings.
I will say that what I told Blanco about the majority of piston people and reps being utterly clueless though is certainly true. We have crap right now in the shop from a very big name race engine builder that has only done a few LS1s and a huge piston outfit sold him the stuff in this engine and it was major money too. It burns a quart of oil per 100 miles and is new.
The block was done perfectly by this race engine builder and yet because of the asinine piston design used with this perfectly normal and expertly put together 6.125 rodded 4.000 stroke deal it was a giant smoking POS. The skirts had over .010 taper in them and were basically straight taper being biggest at the bottom. These had long "stable" skirts and with .0045 cold clearance still rocked .050 at the top and almost .150 at the bottom.
These pistons cost 1800.00 and were not expedited.
The rings cost 267.00 and had napier seconds.
That engine made 83 more rwhp when the correct 500.00 pistons and 75.00 rings were installed and no more smoke and no more excessive crankcase pressure.
A resident piston expert at this company said that they thought the cylinders were 6.000 long but still couldn't explain the nearly .011 total taper. Fortunately this company is one of the most popular piston companies for the american V8 market but is not a regular player on this bulletin board.
I will say that what I told Blanco about the majority of piston people and reps being utterly clueless though is certainly true. We have crap right now in the shop from a very big name race engine builder that has only done a few LS1s and a huge piston outfit sold him the stuff in this engine and it was major money too. It burns a quart of oil per 100 miles and is new.
The block was done perfectly by this race engine builder and yet because of the asinine piston design used with this perfectly normal and expertly put together 6.125 rodded 4.000 stroke deal it was a giant smoking POS. The skirts had over .010 taper in them and were basically straight taper being biggest at the bottom. These had long "stable" skirts and with .0045 cold clearance still rocked .050 at the top and almost .150 at the bottom.
These pistons cost 1800.00 and were not expedited.
The rings cost 267.00 and had napier seconds.
That engine made 83 more rwhp when the correct 500.00 pistons and 75.00 rings were installed and no more smoke and no more excessive crankcase pressure.
A resident piston expert at this company said that they thought the cylinders were 6.000 long but still couldn't explain the nearly .011 total taper. Fortunately this company is one of the most popular piston companies for the american V8 market but is not a regular player on this bulletin board.
George
01-26-2008, 12:26 PM
#23
FormerVendor
The stroke like I said depends on how long the cylinder is and how much ringstack you need etc. I run the 4.250 quite a bit with the longer cylinder stuff but not with the regular cylinders which are way shorter. When I do run that stroke it is for mostly NA usage as obviously the pistons are not going to be big NOS pistons but that goes without saying.
01-26-2008, 02:05 PM
#24
I don't do that combo either since the cylinders are just not long enough. The CH is not the issue but rather the problems at BDC. I don't even do many 4.125 deals in a reg length cylinder because of this but rather mostly 4.100s or my piston gets too cramped for rings.
I will say that what I told Blanco about the majority of piston people and reps being utterly clueless though is certainly true. We have crap right now in the shop from a very big name race engine builder that has only done a few LS1s and a huge piston outfit sold him the stuff in this engine and it was major money too. It burns a quart of oil per 100 miles and is new.
The block was done perfectly by this race engine builder and yet because of the asinine piston design used with this perfectly normal and expertly put together 6.125 rodded 4.000 stroke deal it was a giant smoking POS. The skirts had over .010 taper in them and were basically straight taper being biggest at the bottom. These had long "stable" skirts and with .0045 cold clearance still rocked .050 at the top and almost .150 at the bottom.
These pistons cost 1800.00 and were not expedited.
The rings cost 267.00 and had napier seconds.
That engine made 83 more rwhp when the correct 500.00 pistons and 75.00 rings were installed and no more smoke and no more excessive crankcase pressure.
A resident piston expert at this company said that they thought the cylinders were 6.000 long but still couldn't explain the nearly .011 total taper. Fortunately this company is one of the most popular piston companies for the american V8 market but is not a regular player on this bulletin board.
I will say that what I told Blanco about the majority of piston people and reps being utterly clueless though is certainly true. We have crap right now in the shop from a very big name race engine builder that has only done a few LS1s and a huge piston outfit sold him the stuff in this engine and it was major money too. It burns a quart of oil per 100 miles and is new.
The block was done perfectly by this race engine builder and yet because of the asinine piston design used with this perfectly normal and expertly put together 6.125 rodded 4.000 stroke deal it was a giant smoking POS. The skirts had over .010 taper in them and were basically straight taper being biggest at the bottom. These had long "stable" skirts and with .0045 cold clearance still rocked .050 at the top and almost .150 at the bottom.
These pistons cost 1800.00 and were not expedited.
The rings cost 267.00 and had napier seconds.
That engine made 83 more rwhp when the correct 500.00 pistons and 75.00 rings were installed and no more smoke and no more excessive crankcase pressure.
A resident piston expert at this company said that they thought the cylinders were 6.000 long but still couldn't explain the nearly .011 total taper. Fortunately this company is one of the most popular piston companies for the american V8 market but is not a regular player on this bulletin board.
D.J.
01-26-2008, 02:45 PM
#25
FormerVendor
It would appear the engine builder you refer to here did not check those pistons or didn't know what to look for if he did. The build sheet for those pistons should have shown where to measure them at, (some defined location below the pin centerline and 90 degrees from the pin's cross section) to set up the cylinder wall clearance. All someone would need to do was to continue to side the mic down from the manufactures measurement point to the bottom of the skirt to see an error, (a taper in this case). From what you have said here the widest point of these piston's was at the bottom and tapering to the top. This put the widest cross section of the piston sticking out of the cylinder at BDC if I'm reading this correctly. Hence the .150" rock. Unless I'm way off base here, this is common engine building practice and not just an issue with the LSX platform. While it is true these engines don't have extremely long cylinder sleeves in them we are only looking at a 4" stroke in this case, (stock for an LS-7). I'm not an engine builder so please correct me if I'm wrong.
D.J.
D.J.
They were unaware of how short the cylinders were AND they also shouldn't have run a profile like that on a street engine without telling them that it would not work well untill you were putting 1500+hp through it. The piston guy was simply playing it safe since they didn't want to stick a piston and the combo never stuck a piston.
It just smoked really bad and ran like crap since it only really made 800 hp and had 5.500 long cylinders. The pistons just simply couldn't do their job correctly since they were not designed right.
01-26-2008, 02:51 PM
#26
FormerVendor
DJ,
Also most small block engines running 4 inch stuff and up do have longer cylinders than the normal LSx engines do. This is why on the LS7 with the longer cylinders you have room to keep much more skirt in the bore and guiding the pistons so this scenario doesn't happen to you.
I run some crazy stuff but it has non conventional pistons when we run a really short bore length. I even run the 4.100 all the time in the OEM length bore but we use our own piston that is happy in this application and it's not a big NOS setup.
Also most small block engines running 4 inch stuff and up do have longer cylinders than the normal LSx engines do. This is why on the LS7 with the longer cylinders you have room to keep much more skirt in the bore and guiding the pistons so this scenario doesn't happen to you.
I run some crazy stuff but it has non conventional pistons when we run a really short bore length. I even run the 4.100 all the time in the OEM length bore but we use our own piston that is happy in this application and it's not a big NOS setup.
01-26-2008, 03:25 PM
#27
Thanks Erik for clearing some of this up for me.
The pistons used in the engine you repaired were set up to grow under the extreme heat of an NOS or some sort of forced induction application. I would assume a piston could be made to address this application if the piston break point was in the correct location. While not ideal it could live under race only conditions.
D.J.
The pistons used in the engine you repaired were set up to grow under the extreme heat of an NOS or some sort of forced induction application. I would assume a piston could be made to address this application if the piston break point was in the correct location. While not ideal it could live under race only conditions.
D.J.
01-26-2008, 03:46 PM
#29
On The Tree
Thread Starter
iTrader: (2)
Join Date: Mar 2002
Location: Houston, Texas
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
"We can make a pistons for the 4.250 stroke and the 6.200 rod but, it will get you only a .915 compression height. Which is very small for a street car. We can make piston with .750 compression heights but, it is not something that we do everyday. Just wanted to clear that up, we can make the piston I just would not advise it for street use.
Thanks,
Chris Gelineau
Diamond Pistons"
So diamond says not for street so that means no longivity
George
Thanks,
Chris Gelineau
Diamond Pistons"
So diamond says not for street so that means no longivity
George
01-26-2008, 09:47 PM
#33
FormerVendor
Yes but I wouldnt go right out and use up too much bore on a stock LS7 block though. I do the Sleeved blocks like the Dartons at bigger bores even up to 4.185 and Steve at RED and ERL have them running at even larger bores up to 4.200 on some apps. The rings get really sparse in some of those sizes though.
01-26-2008, 10:01 PM
#34
FormerVendor
The sleeve length and rod length and the ring stack determine how much skirt is left in the bore at the bottom. We don't use a 6.200 rod with the 4.250 stroke but rather a different rod. The rod length, stroke and deck height tell you how much CH and ring stack you can run.
01-26-2008, 10:12 PM
#35
Banned
iTrader: (5)
Join Date: Apr 2003
Location: Chicago
Posts: 1,890
Likes: 0
Received 0 Likes
on
0 Posts
After going though one of these warhawk blocks, they are expensive, once you figure in all the extra machine work thats basically imperative for an LSX block, the warhawk has real billet main caps, ARP main studs when you add it up, the extra price of a warhawk is maybe under $1,000 over building an LSX?
now the warhawk needs the parts kit, that includes ARP head studs which are needed anyway, the valley cover, most people have to purchase an LS2 valley cover anyway; when they build an LSX.
1/2 the LSX blocks we've had built needed to be align bored.
01-26-2008, 10:13 PM
#36
FormerVendor
Steve told me these are 5.800 long sleeves.
I mentioned after the referenced quote that I found it was the .100 shorter than the LS7, and they are supposed to be 5.900. What he told me was, mine are .350 longer than the LS2, my bad. Sorry
This is what I found after a search.
I mentioned after the referenced quote that I found it was the .100 shorter than the LS7, and they are supposed to be 5.900. What he told me was, mine are .350 longer than the LS2, my bad. Sorry
This is what I found after a search.
The real problem is the fact that the shops first doing those particular 8000.00 C5R blocks were too damn lazy to measure all the way to the bottom to see that the walls were doing that. That was one of the first stories I relayed to Steve there when requesting longer sleeves in my Darton stuff. This is part of the reason the LSX bore length is normal OEM length as some hones can't hone as low as others without hitting the main webbing. The Sunnen CK and CV hones can though.
01-27-2008, 12:43 AM
#37
TECH Fanatic
iTrader: (1)
Join Date: Oct 2002
Location: Elmhurst, IL (Chicago Suburb)
Posts: 1,851
Likes: 0
Received 0 Likes
on
0 Posts
ERIK,
Get some rest man! Great info and insight you have added here. I see you will be building another motor like mine from a local referral here in Chicago (Elvir) that I sent your way.
Like you need the extra work, right? LOL
Get some rest man! Great info and insight you have added here. I see you will be building another motor like mine from a local referral here in Chicago (Elvir) that I sent your way.
Like you need the extra work, right? LOL
