4.0 liter 964 engine project
02-06-2009, 05:22 PM
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4.0 liter 964 engine project
I will start to rebuild my1991 964 engine and I am thinking to use ln engineering 105mm kit but I wonder if I can use my stock components like injectors,fvd hot air maf conversionwith chip ,etc?
02-06-2009, 11:06 PM
#2
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The stock fuel injectors will support approximately 305hp, so if you have an engine combination that makes more power than that, you will need to EITHER, increase your fuel pressure (and associated engine mapping) OR install larger injectors (and associated engine mapping). Most likely you will need to have your engine remapped and if the airflow is more than the MAF can handle, it will be outside the range that the engine will be able to be mapped.
It sounds like you need some help developing a complete engine build strategy rather than installing parts...
It sounds like you need some help developing a complete engine build strategy rather than installing parts...
02-07-2009, 11:14 AM
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02-07-2009, 05:06 PM
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I wasn't in any way implying that Colin was better. I merely suggested him as i know he has built a few 4.0 litre engines for the 964.
Hope that clears up any misunderstandings.
Regards
Martin
www.964rsdatabase.com
Hope that clears up any misunderstandings.
Regards
Martin
www.964rsdatabase.com
02-08-2009, 06:51 AM
#6
Burning Brakes
You're right - if you want to spend a fortune to get a car that blows up regularly then you are right, he is your man...
Do a search, especially on the turbo forums, before you recommend him.
Do a search, especially on the turbo forums, before you recommend him.
02-09-2009, 11:46 AM
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I concur with Geoffrey that you need to develop a complete engine development strategy rather than be swayed by the glamour of a large capacity engine.
That said, you can acheive a 4.0 litre capacity by retaining the stock stroke and increasing the bore or by increasing both the stroke & bore.
In general terms, increasing the bore on a stock stroke will allow the engine to run at higher rpms due to reduced rod loadings, however it also places a larger flow demand on the intake port/valve combination and radically alters the combustion characteristics of the chamber.
Keeping the piston near to stock & using the longer stroke minimises the changes required for the head/port/valve combination, however it does increase rod loadings due to a higher piston speed so using a lightweight piston is important to compensate for that.
We have done a lot of work optimising the 9m billet heads for intake flow and combustion, hence why we use an 80.0mm stroke with a 103.0mm bore to achieve exactly 4.0 litres. Obviously our design decisions are not too far away from ideal, as the new 4.0 litre Porsche 997GT3RSR engine uses a similar 80.4mm x 102.7mm stroke/bore combination.
That said, you can acheive a 4.0 litre capacity by retaining the stock stroke and increasing the bore or by increasing both the stroke & bore.
In general terms, increasing the bore on a stock stroke will allow the engine to run at higher rpms due to reduced rod loadings, however it also places a larger flow demand on the intake port/valve combination and radically alters the combustion characteristics of the chamber.
Keeping the piston near to stock & using the longer stroke minimises the changes required for the head/port/valve combination, however it does increase rod loadings due to a higher piston speed so using a lightweight piston is important to compensate for that.
We have done a lot of work optimising the 9m billet heads for intake flow and combustion, hence why we use an 80.0mm stroke with a 103.0mm bore to achieve exactly 4.0 litres. Obviously our design decisions are not too far away from ideal, as the new 4.0 litre Porsche 997GT3RSR engine uses a similar 80.4mm x 102.7mm stroke/bore combination.
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02-10-2009, 09:02 AM
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If you are thinking of using them with pistons that are commonly available for the 911 aircooled engine, it would be the equivalent of fitting Cup car one-piece carbon/kevlar doors to a cooking 996 tiptronic C4S and claiming that you have made a significant weight saving.....
Rod end weight is highly significant on a high rpm, low inertia engine, the stock 964 is neither of these things, therefore any perceived benefit will be negligible in this application. However if you came up with a radical design of 911 aircooled valve train that would run at 10,000rpm, combined it with low inertia crank and fitted metal matrix composite pistons weighing 350g on the end of your long Titanium rods you may want to consider ti pins as a feasible option provided you are willing to replace them every 30 hours running.
Rod end weight is highly significant on a high rpm, low inertia engine, the stock 964 is neither of these things, therefore any perceived benefit will be negligible in this application. However if you came up with a radical design of 911 aircooled valve train that would run at 10,000rpm, combined it with low inertia crank and fitted metal matrix composite pistons weighing 350g on the end of your long Titanium rods you may want to consider ti pins as a feasible option provided you are willing to replace them every 30 hours running.