Tall or short (ports)
#26
Hunting Skylines
Join Date: Apr 2001
Location: Brisbane, Queensland, Australia.
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Originally Posted by rotarygod
I'd have the header ceramic coated with this technique though. It gets VERY hot!
#27
The General RE
Originally Posted by rotarygod
... He modified it so that the primaries were bridged with each other and the secondaries were bridged with each other...
#28
Rotors still spinning
iTrader: (1)
Originally Posted by REVHED
What sort of effect does the heat have on the exhaust turbine in turbocharged applications?
#29
Old Fart Young at Heart
iTrader: (6)
Jeff, you have too many parts to play with and too many options between all of them. I'm having touble keeping track of all of it.
Personally, for the REPU, I would try the tall port center iron with the reverse runner intake. That would give you the longest primays out of the bunch for low rpm torque and a short run, higher volume for the secondarys, depending on how much you port the runners.
Personally, for the REPU, I would try the tall port center iron with the reverse runner intake. That would give you the longest primays out of the bunch for low rpm torque and a short run, higher volume for the secondarys, depending on how much you port the runners.
#30
Moderator
iTrader: (3)
Originally Posted by rotarygod
Take an appropriately sized pipe and shape one end of it down to an oval. Then cut the ovaled end at a 20 degree angle. Now insert this into the rotor housing from the exhaust flange side. ... I'd have the header ceramic coated with this technique though. It gets VERY hot!
Originally Posted by rotarygod
You absolutely MUST have an inconel turbine wheel. If you don't, it will melt!
#33
Rotors still spinning
iTrader: (1)
Originally Posted by diabolical1
what type of material would be appropriate for the pipe? would it do just to have it ceramic coated like the header or would you have to use something special, like Inconel?
#34
Seeking to finalize my projects.
REPU:
3B plates smoothed etc
rotor housings to T2 or there abouts
MG:
Y plates to '74 spec
rotor housings unported
Baja:
Y plates smoothed etc
J-spec rotor housings unported
Reasons REPU:
I'd prefer a Y intermediate for forced induction, but I may never get around to it. Besides, if I can afford a supercharger, I can probably also afford a quickie rebuild. Moreover, a nitrided set of sideplates would hold up better to boost, I'd think, under normal circumstances (as long as it doesn't exceed the strength limitations of the rear plate, which the lighter, weaker Y plates and S4 are known to fail at the dowel pin area near the oil filter pedestal, which on the 3B plate is reinforced like later S5, S6 etc). Or I could have a custom manifold ported to match the '74-'75 short port plate, maybe. I'm thinking too much. The soon to be T2 ported rotor housings have 99% perfect chrome so they should last a while and have better compression than the stock ported ones. Only the really low RPM torque will be affected - not really a big issue in a '74 REPU with 4.625 gearing, stock heavy flywheel, and it won't be hotrodded much. My other REPU with D ported rotor housings, missing chrome, nitrided R5 plates, streetports etc. can tow things pretty well, and it's NA.
Reasons MG:
Some missing chrome. One housing was junked. Its replacement is in similar shape to the other, and can be reused. No plans to go forced induction on the MG. Liked the way it took off on primaries with the Cosmo manifold. For safety, I should limit or govern the high end power/high speed driving capabilities until such time as I can afford to redo the suspension, brakes etc. Keeping the exhaust ports stock should help. I feel the '74 spec intake ports are ideal as there is no need for the ultra low end of stock intake ports, they happen to be compatible with the small exhaust ports, and there is not enough carburetion available for street ports with the current setup (which actually fits). A good middle of the road with room for future improvement once the suspension and brakes are sorted out.
Reasons Baja:
I've already stated the reasons for the baja, but I should touch on them again. I'm obviously not happy with the bug engine. If I was, I wouldn't have invested the time and effort you've seen here over the last two weeks asking all these questions about ports and all that. It can barely break 'em lose in snow! It takes so long to respond to throttle inputs that by the time it finally gets up there, the oppurtunity has already passed. Not happy at all. I'm willing to invest time and effort to make a reliable watercooled swap work. Not a fan of piston engines in general, and I'm discovering I'm not a fan of air cooled either. It's quirky, but quirky has little staying power, you know?
I could go on ranting about it all day, but I won't. Ok, Y side plates for lightness, no porting for ultra low end, J-spec exhaust port timing for better low end peaking at like 4k RPM, 97% perfect chrome (good enough for me), S4 T2 waterpump for lightness and hopefully efficiency too, beehive for ease of installation and no oil lines to tear off, tall radiator mounted in the front for best cooling. I'll get a bus tranny for it some day.
I've been over this project mentally dozens of times and it always comes down to time and money, effort and desire. If I have all four, I'm good to go. Just gotta finish two projects first.
REPU:
3B plates smoothed etc
rotor housings to T2 or there abouts
MG:
Y plates to '74 spec
rotor housings unported
Baja:
Y plates smoothed etc
J-spec rotor housings unported
Reasons REPU:
I'd prefer a Y intermediate for forced induction, but I may never get around to it. Besides, if I can afford a supercharger, I can probably also afford a quickie rebuild. Moreover, a nitrided set of sideplates would hold up better to boost, I'd think, under normal circumstances (as long as it doesn't exceed the strength limitations of the rear plate, which the lighter, weaker Y plates and S4 are known to fail at the dowel pin area near the oil filter pedestal, which on the 3B plate is reinforced like later S5, S6 etc). Or I could have a custom manifold ported to match the '74-'75 short port plate, maybe. I'm thinking too much. The soon to be T2 ported rotor housings have 99% perfect chrome so they should last a while and have better compression than the stock ported ones. Only the really low RPM torque will be affected - not really a big issue in a '74 REPU with 4.625 gearing, stock heavy flywheel, and it won't be hotrodded much. My other REPU with D ported rotor housings, missing chrome, nitrided R5 plates, streetports etc. can tow things pretty well, and it's NA.
Reasons MG:
Some missing chrome. One housing was junked. Its replacement is in similar shape to the other, and can be reused. No plans to go forced induction on the MG. Liked the way it took off on primaries with the Cosmo manifold. For safety, I should limit or govern the high end power/high speed driving capabilities until such time as I can afford to redo the suspension, brakes etc. Keeping the exhaust ports stock should help. I feel the '74 spec intake ports are ideal as there is no need for the ultra low end of stock intake ports, they happen to be compatible with the small exhaust ports, and there is not enough carburetion available for street ports with the current setup (which actually fits). A good middle of the road with room for future improvement once the suspension and brakes are sorted out.
Reasons Baja:
I've already stated the reasons for the baja, but I should touch on them again. I'm obviously not happy with the bug engine. If I was, I wouldn't have invested the time and effort you've seen here over the last two weeks asking all these questions about ports and all that. It can barely break 'em lose in snow! It takes so long to respond to throttle inputs that by the time it finally gets up there, the oppurtunity has already passed. Not happy at all. I'm willing to invest time and effort to make a reliable watercooled swap work. Not a fan of piston engines in general, and I'm discovering I'm not a fan of air cooled either. It's quirky, but quirky has little staying power, you know?
I could go on ranting about it all day, but I won't. Ok, Y side plates for lightness, no porting for ultra low end, J-spec exhaust port timing for better low end peaking at like 4k RPM, 97% perfect chrome (good enough for me), S4 T2 waterpump for lightness and hopefully efficiency too, beehive for ease of installation and no oil lines to tear off, tall radiator mounted in the front for best cooling. I'll get a bus tranny for it some day.
I've been over this project mentally dozens of times and it always comes down to time and money, effort and desire. If I have all four, I'm good to go. Just gotta finish two projects first.
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