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What's the maximum Reliable RPM Limit on the 4G63 Head
Hi folks. I'm building a high rpm 4g61, with a 4g63 head. I'm curious to know what are your views regarding the maximum rpm limit is, based on the design of these cylinder heads. Please don't flood with comments about not needing to rev the engine high at all. This project is being built for a specific purpose, which necessitates high rpm operation. Look forward to your answers.
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need more details on your setup...
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what did a 4g61 come in? do you mean 4g64?
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The 4G61T came in the late eighties Mitsubishi Mirage. It is a 1595cc version of the 4G63T. The block is identical to the 63. The big differences being the deck height is shaves 6mm. In addition the stroke is 75.5mm as opposed to the 63's 88mm. The bore is 82.5mm stock. This yeilds a far superior rod ratio to the 63. The rods and cylinder head are interchangeble with the 63.
My setup: Custom 83.5mm 10.0:1 Ross Pistons Carillo Rods w/ ARP Fastners ARP Head Studs, Mains, etc MLS Head Gasket Brian Crower Stage 3 Cams Ferrea Dual Interferance fit Springs, w/Ti Retainers Adjustable Gears DNPerformance Tubular Header FP3052 Turbocharger Ferrea 1mm OS Valves Extrude Honed Stock Intake Manifold Ported and Polished 1g Head Fluidampr Harmonic Balancer Custom Moroso 3-Stage Dry Sump Kit Evolution 8 Intercooler Haltech E6X ECU |
the max rpm of the head would be determined by the valve springs and the lifters.
eg. if your springs can handle 10,000rpm and your lifter can handle 9000rpm then your head can handle 9000rpm. The bottom end is a different story Which lifters do you have? With 10.1 comp what oct gas are you using? This is a race setup, what are you doing (dexterity, hillclimb)? post some pictures of your setup |
With a cam lift under 11 mm, and a good set of valve springs such as kiggly racing's set, 10,000 rpm isn't a problem. I'm running a set of Brian Crower 280's and the Kiggly springs. I reved it to 10,000 rpm several times, and 9750 a whole season without any issues.
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Are there any issues with timing belt stretch, lifter pump up, or rocker arm instability?
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Originally Posted by kduncan01
(Post 5591044)
the max rpm of the head would be determined by the valve springs and the lifters.
eg. if your springs can handle 10,000rpm and your lifter can handle 9000rpm then your head can handle 9000rpm. The bottom end is a different story Which lifters do you have? OEM 1st Gen With 10.1 comp what oct gas are you using? E85 This is a race setup, what are you doing (dexterity, hillclimb)? Road Race post some pictures of your setup |
I am not sure what the OEM lifter can handle, JAM has a lifter that can handle 9500RPM you may want to check into that
Do you race at Dover? |
Yes I do race at Dover. Can you provide some more info on the JAM lifters???
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Originally Posted by kduncan01
(Post 5597966)
I am not sure what the OEM lifter can handle, JAM has a lifter that can handle 9500RPM you may want to check into that
Do you race at Dover? |
If you really want ot spin the snot out of a dsm head, there is a company that makes solid lifters.. I think it was B.R.E. or C.R.E...
google search for solid lifter 4g63, and i think it ought to pop up... Correction... it was B.L.E. the old extreme race car used them... |
I can not wait to see some numbers from this motor.
Keep the info coming! |
https://www.jacksonautomachine.com/h...m?sectionId=17
Here is the link, second item down. Greg from GSC first put me on these, I called JAM and and spoke with them. Call them and speak with Camila it incredible how much she knows. I dont know how high you want to rev but 9000-9500 can be done on HYD lifters and you dont have to go to solid. Spend some pics of Dover |
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