Mike Simard

JEC31, is this the engineering forum you're thinking of? http://www.eng-tips.com

Brendan, do you think striaght cut gears would help transmission strength or are the shafts flexing from being long and unsupported? I do wish someone would make a straight tooth, dog-ring gearset that could be swapped in.

Stig, there's the Mercedes 6.9! One showed up at a Grassroots Motorsports 200x challenge, The guy bought it for just under the $2000 limit and didn't do anything to it. Say, you could probably hone .1 liter out of the bores and have a 427!
The Nikasil sleeve has no reason to have a coated piston although it can be done for even more reduced friction. I'm not going to coat the pistons, one consideration was to have the sleeves extend down as far as possible thereby supporting the pistons as the come out of the sleeves at the bottom stroke. The bottom edge is also radiused there. I've built engines with longer strokes and have seen signs of scruffing on the skirt not related to materials but poking out of the clylinder with a sharp edge, even some rubbing the cylinder edge with 400 sandpaper wasn't enough, a skirt can rock based on clearance and how far it pokes out and IMHO the edge has to be broken more than is thought.

Vilhuer

Very interesting project and high quality work Mike. Your sleeves looked so much like Darton's that I jumped to conclusion they must be from them. I have been looking into making sleeves from iron cylinder liners which are used in tractors and other heavy machinery. They would be installed same way as you are doing yours. Reason for looking something which is relatively close in size instead of making from scratch is that I do not have similar possibilities as you have. Minimizing amount of machine work might pay of in $$$ needed. So far have managed to find some possibilities which might work but 108mm bore could be bit too much. Still looking for 106mm range. I have no idea what exact measurements should be for them to seal properly against block and so on. If you don't mind, I'll send you PM once I have some more specific questions to ask.

As for the gearbox. There is local 928 track car project which has been killing early boxes little too frequently. Owner has decided to have straight cut gears made. AFAIK they will use G28.03 or 05 casting and build practically everything inside from scratch. We have few shops which really know what they are doing and can make practically indestructable gearboxes. Prices are grazy though. One example is:

http://www.ssf-pyora.fi/uk/index.html

BC

I think Todd is the most honest guy I have met when it comes to explaining what he is doing. I ask him stuff weekly. PM me or hacker and I am sure we would be able to get you his info. Todd T, a resident of Green Bay Packer Land.

Mike Simard

Some more pics:
1-Inside of the block showing the o-ring groove
2-the sleeves after some rough machining and heat treating, still lots to cut.
3-LS7 Titanium rod, they weigh 480 grams and are forged. The big end is the normal 2.1 x .94, pin is .926, the center to center is 6.068 which is about as long as a rod can be with the 3.7 stroke and 9.134 deck height. Aside from the usual compression height measurement of pin to piston top, the small end of the rod is getting close to the inside of the piston. The rods have a coating on the lower half for lubricity of the big end widths, the small end has a grooved bronze bushing.

BC

Can you tell us how much those Ti Rods were? Oliver steel rods are usually about 2k right? But since those are stock Chevy parts, the price should be lower.

Mike Simard

The LS7 rods seem to be going for $2300. When they first came out they were priced at some silly low figure, I think $80 ea. or something like that, it seemed to have been a mistake and was corrected, I don't know if they sold many or not but they deleted the part number along with the price and they're now sold at an appropriate price under a different number. Steel Olivers should be much cheaper, any titanium is going to be a bunch more, the stuff is a bear to work with and just the raw material to make 8 rods would be significant. I'd considered buying titanium stock to machine a set and it would have cost almost $1000 for the material, a forging would use less than machining a plate but still. Another factor is the forging, they're superior structurally to a machined billet.

BC

[QUOTE=Mike Simard]The LS7 rods seem to be going for $2300. When they first came out they were priced at some silly low figure, I think $80 ea. or something like that, it seemed to have been a mistake and was corrected, I don't know if they sold many or not but they deleted the part number along with the price and they're now sold at an appropriate price under a different number. Steel Olivers should be much cheaper, any titanium is going to be a bunch more, the stuff is a bear to work with and just the raw material to make 8 rods would be significant. I'd considered buying titanium stock to machine a set and it would have cost almost $1000 for the material, a forging would use less than machining a plate but still. Another factor is the forging, they're superior structurally to a machined billet.[/QUOTE

Is that price in line with other Ti Rods? The rod length makes the r/s ratio about 2?

480g for the rod - what would a billet steel rod weigh, or whatever Carillo or Oliver tout as thier High HP steel rod?

Mike Simard

A steel Carillo rod would be in the 600 range, I beleive a stock 928 rod is more than that. Titanium is 40% lighter than steel but less strong so a rod would have more material, it works out to about 20% weight reduction. The rod/stroke ratio is 1.62:1 on this engine. An LS7 is 1.52 so this is an improvement. An LS7 seven motor can only dream of this kind of bore capacity and valve count

Mike Simard

860? Yikes. I just tossed a stock rod and piston assembly on a scale and it was about 1600 grams approx, damn. When my rods arrived I picked up the box and thought it was a partial shipment or some had been lost. In the past when a set of steel rods came in I thought the box felt full of bricks.

Vilhuer

Probably best custom Ti rods can be found from Finland. There are few places which have specialised in doing these from grade5 (Ti6Al4V). Drag racers in US use these shops. Prices are crazy though, average nothing special versions are around $4k for set of 8.

JEC_31

[QUOTE=Mike Simard]JEC31, is this the engineering forum you're thinking of? http://www.eng-tips.com

QUOTE]


Yes! Thanks, I've got it saved now. Might even join to ask questions, but I know I'm way over my head there.

Keep up the good work, can't wait to see your dyno sheet!

slate blue

As to rods I think any new prospective engine builder should consider Honda rods. This is what I have, the advantages are quite a few, low weight, we'll get back to that but they are cheap. Especially cheap if you get a barely used set. My sets had less than 400 miles on them. They cost me $500 for two sets, I will get them checked and closed and honed if I have to. The bolts are those top end SPS Carr bolts. The bolts are close to $700 as an outright purchase.

So you get reduced bearing speed which means less friction, you also have a less weighty big end, remember the honda journal is 48 mm diameter and the chevy is about 53 mm. I haven't worked it out but that is probably a 20% or so reduction in the weight of the journal. That is saving you a lot of mass and the forces that come with that mass.

You also will make more power due to the reduced friction, 7 hp is the industry standard at 7000 rpm the weight for my rods which are fully machined forgings. is 542 grams and the rod length is 6.2" I think you will also have more room in the sump with these parts.
Here's a pic

Ti is good no doubt about it, but the Nascar rods are great too and at a 10th of the price, they are also high tech, some even have forced pin oiling, you need to becareful which rods you buy as the're good and bad rods out there. Mine had no heat issues and the maker of the rod would reco it if need be.

Cheers Greg

slate blue

Mike I really like your project, especially the Nicasil couting of the barrels, that is smart. What type of pistons are you going to use for this baby?

mark kibort

But, if you are only spinning the engine up to 6000rpm, that 7hp becomes 4hp.
And, the forces are much less. I think we are in good shape with most any rod combination. even the stock 848gram rods from porsche are tough and dont really have any adverse effects on longevitiy. I think the bmw and porsche guys, twisting their engines up to 8000 to 9000rpms need to REALLY be concerned with this rotating mass weight thing!

MK

123quattro

I built an engine for my Audi this spring. Factory forged rods were forced pin oiling. Those rods were good to 400 hp or there about. I got a set of rods from 034 Motorsport that look a lot like Eagle rods. They aren't forced oiling on the wrist pin, but are H beam instead of I and are known good to 800 hp @ 9000 rpm. I was really surprised to see the change in wrist pin oiling, especially for a high hp rod. However, their track record is well proven.