What Are The Engine Differences

[cly_mitchell]

I was just compairing models. It is hard to discern the differences in the HC,SE, and the sport 300. It apears on the outside the SE is a coolcharged HC, with more boost, and fuel of course. The compression is the same. The dispacement is the same. Is the bottom end different? Is the top end different? It also appears the sport 300 is the same basic motor but with more boost. Just curious. (not like that ) I understand the transmission is different and the chassis was updated, and the ignition is different. But did the core of the motor change?

[chandrab]

Don't forget that the SE/Sport 300 had GM GMP4 Engine Computer vs. the Bosch unit of the earlier cars. The SE had Nikasil liners also. I'm sure someone knows the complete changes as I've seen them before.

-Chandra

91SE

I was just compairing models. It is hard to discern the differences in the HC,SE, and the sport 300. It apears on the outside the SE is a coolcharged HC, with more boost, and fuel of course. The compression is the same. The dispacement is the same. Is the bottom end different? Is the top end different? It also appears the sport 300 is the same basic motor but with more boost. Just curious. (not like that ) I understand the transmission is different and the chassis was updated, and the ignition is different. But did the core of the motor change?

[Artie]

Don't forget that the SE/Sport 300 had GM GMP4 Engine Computer vs. the Bosch unit of the earlier cars. The SE had Nikasil liners also. I'm sure someone knows the complete changes as I've seen them before.

-Chandra

91SE

Don't be so sure someone really knows the differences. I inquired about the "alleged" chrome topping on the SE pistons VS the NON SE pistons to John Welch and he wasn't sure of what I'm talking about. I think the internals are the same on the block, rods, pistons and displacement. The differences stem from the hea, valves and such.

Artie

[Vulcan Grey]

Don't be so sure someone really knows the differences. I inquired about the "alleged" chrome topping on the SE pistons VS the NON SE pistons to John Welch and he wasn't sure of what I'm talking about. I think the internals are the same on the block, rods, pistons and displacement. The differences stem from the hea, valves and such.

Artie

The pistons are different for each engine; 910, 910 cc, 912, 920... IIRC

My 910 chargecooled SE pistons are definitely chrome plated (or were)

the 920 is nickel.

the Sport 300 had ddiffernet cylinder head. The intake valves are larger, and it is ported and polished IIRC.

The deck height on the 920 is different of course.

The Charge cooled cars have a different valve cover on the intake

DOn't know much about the HC. But I wonder what pistons and valves it has? Are the pistons forged, are the valves sodium filled?

[Artie]

Travis, the 910 base engine(for both chargecooled and non chargecooled) are supposed to be the same right? I figured the block, rods, pistons etc were the same. I wonder if my pistons are chrome topped too. Theoretically they should be correct? Are you gettting new pistons or having your treated with skirt coatings etc?

Artie

The pistons are different for each engine; 910, 910 cc, 912, 920... IIRC

My 910 chargecooled SE pistons are definitely chrome plated (or were)

the 920 is nickel.

the Sport 300 had ddiffernet cylinder head. The intake valves are larger, and it is ported and polished IIRC.

The deck height on the 920 is different of course.

The Charge cooled cars have a different valve cover on the intake

DOn't know much about the HC. But I wonder what pistons and valves it has? Are the pistons forged, are the valves sodium filled?

[Vulcan Grey]

Travis, the 910 base engine(for both chargecooled and non chargecooled) are supposed to be the same right? I figured the block, rods, pistons etc were the same. I wonder if my pistons are chrome topped too. Theoretically they should be correct? Are you gettting new pistons or having your treated with skirt coatings etc?

Artie

I believe the block and lower end is the same...

I had my pistons (grade A) coated with ceramic on the crowns and Tungsten& Molybdenum disulfide on the skirts.

I had the cylinders recoated with Nikasil.

Then I got such a good deal on a full new set of pistons, cylinders,rings, and grudgeon pins from the Lotus sale, that I bought those too...

Now just have to make up my mind.

[Artie]

I believe the block and lower end is the same...

I had my pistons (grade A) coated with ceramic on the crowns and Tungsten& Molybdenum disulfide on the skirts.

I had the cylinders recoated with Nikasil.

Then I got such a good deal on a full new set of pistons, cylinders,rings, and grudgeon pins from the Lotus sale, that I bought those too...

Now just have to make up my mind.

Awesome, either way you'll have a set of spares that I can buy when your mind is made up! Better to have and not need than need and not have! Special forces motto!

Who did you get the pistons from? Are they Lotus (mahle) pistons or didi you go with the JE? I don't need a rebuild just yet, but I am thinking along your lines, I may pull the engine next winter and have John Welch build me a fresh one. Did you use H beam rods or are you retaining the stock I beams? I am talking to a guy that works for Pauter and trying to see about possibly getting some forged aluminum rods if they aren't too different in size/dimension from other already manufactured parts.

Artie

[cly_mitchell]

I halfway thought this a silly question. But it seems to be valid. Best I can tell from part numbers, the cams, crank, pistons and liners, and exhaust valves, are the same. The only difference I can see is the S4S and 300 have a different intake valve. It is resonable to assume the head porting may be different as well. The engine eletrics are different and the fuel delivery is different.

From what I read, the HC was on the ragged edge of compession and boost. Pre-detonation was putting the motor in stress. It seems the chargecooler was the saving grace. Wayne B has also said as much.

[Artie]

I halfway thought this a silly question. But it seems to be valid. Best I can tell from part numbers, the cams, crank, pistons and liners, and exhaust valves, are the same. The only difference I can see is the S4S and 300 have a different intake valve. It is resonable to assume the head porting may be different as well. The engine eletrics are different and the fuel delivery is different.

From what I read, the HC was on the ragged edge of compession and boost. Pre-detonation was putting the motor in stress. It seems the chargecooler was the saving grace. Wayne B has also said as much.

Chargecooling isn't that complicated with the correctly sourced Chargecooler. I have seen them come up for sale periodically on ebay. The additional fuel will be a requirement should you want to up the boost much more.

Artie

[Vulcan Grey]

Awesome, either way you'll have a set of spares that I can buy when your mind is made up! Better to have and not need than need and not have! Special forces motto!

Who did you get the pistons from? Are they Lotus (mahle) pistons or didi you go with the JE? I don't need a rebuild just yet, but I am thinking along your lines, I may pull the engine next winter and have John Welch build me a fresh one. Did you use H beam rods or are you retaining the stock I beams? I am talking to a guy that works for Pauter and trying to see about possibly getting some forged aluminum rods if they aren't too different in size/dimension from other already manufactured parts.

Artie

I bought the genuine Lotus piston/cylinder sets, which are matched and weight graded within 3g.

normally $1000 each... I paid much much less...

I actually saved $7200+ in the Lotus sale.

[Esprit Aviation]

Hmm, forged aluminum rods???.........I like the idea You would have to entertain all pros and CONS!(pun intended) Things like max rpm. piston weight and forces involved, expansion, etc. Very interesting!!!

I used Crower forged steel in mine. Took out 5lbs w/ 4 rods! Imagine what aluminum would be!!

Cheers, Lee

[Artie]

Hmm, forged aluminum rods???.........I like the idea You would have to entertain all pros and CONS!(pun intended) Things like max rpm. piston weight and forces involved, expansion, etc. Very interesting!!!

I used Crower forged steel in mine. Took out 5lbs w/ 4 rods! Imagine what aluminum would be!!

Cheers, Lee

Yeah, there's always a compromise.....Price is it here! We used all Pauter rods in the TAD I used to work on a crew with, 540cu. in Merlin motors with all aluminum parts(besides the crank of course) but crap they'd turn 10K rpm and make 1600 Hp without even breathing hard. Aluminum rods would be a definite advantage to our lack of low end pickup. Reducing this weight would obviously allow the engine to rev faster with less parasitic loss!

Artie

[karluk29]

think the only reply should be,,,,best engine ever GT3. fact he he he, all the

others just fade away into the big garage in the sky frequently lol