Ive been doing alot of research lately here in japan and so far have come up with not a whole lot concerning a high rpm build in stock displacement of a 3.0L. I want to know if there is any shops out there that build or have built a 9000-10,000rpm C30A with light weight, race balanced engine that can handle high rpms like a AP1 engine F20C. I realize that it would take a really amazing builder to get the balance perfect and costly for internals to achieve such high rpms but would it be possible. For N/A building there are only 2 ways to get more power. Displacement such as building a 3.5L or balancing and engine and raising compression to achieve the same result. Now the high comp 3.0L would have a higher power band and would be good for a track car with alot of weight reduction and balancing and the other would have good low end power for a more stock weight and balance car. I have already gotten most of my weight reduction done to the point that there is almost nothing left to pull out or swap for lighter parts. I dont want to upset the balance so i have been making and replacing stock parts with dry carbon. i am doing custom carbon door panels right now to replace the heavy leather and plastic ones. I want something different then the normal boring to a 3.5L for more power. Since i dont have 25k for a MF308 and whatever else id need to swap it in I was thinking building the C30A. Thoughts?
High RPM NA1 Engine?
- Thread starter nismor32gtr
- Start date
I know one of the limiting mechanical factors in engine rpm (among others) is piston speed or more correctly piston acceleration.
Short stroke engines have lower piston speeds which is why high performance engines are usually short stroke.
At redline the S2000 had a mean piston speed of 25.2 meters per second and the Audi RS4 4.2 l V8 had a speed of 25.7 M/s.
I believe those are the two fastest piston speeds in a road car.
My understanding is high performance street engines generally run at 20-25 m/s, Formula 1 over 25 m/s and fuel dragsters up to 30 m/s.
Our C30A has a piston speed of 20.8 m/s at 8000 rpm which is conservative and why our engines are lasting so long.
Assuming Honda has built in their usual safety factors in the C30 block and reciprocating mass perhaps we can consider a C30 engine could run at S2000 piston speeds, say 25 m/s.
At 25 m/s a C30 would be revving at 9600 rpm.
So a high revving C30 should be mechanically possible but some questions remain.
Are the oem pistons/rods/crank able to handle the inertial loads at 25 m/s with reliability?
One of the engine experts on the forum may be able to answer that.
Perhaps the next most important factor in a high revving C30 would be getting the air fuel mixture into the cylinders.
I believe Jon Martin was the builder of the first 3.8L C30 and I remember him telling me at an NSXPO the biggest problem making power in the 3.8L was the air fuel flow rates.
Others on the forum have spoken of the bottleneck of the C30 intake/valves/heads.
So if the C30 reciprocals are capable of turning say 9500 rpm the engine may be fuel starved and never get there.
Perhaps other Prime members have done work on this and can teach us more on the subject.
Failing that there is a lot of info on the web to read about rev limits and head flow rates so perhaps you can research that and share it with the rest of us.
Short stroke engines have lower piston speeds which is why high performance engines are usually short stroke.
At redline the S2000 had a mean piston speed of 25.2 meters per second and the Audi RS4 4.2 l V8 had a speed of 25.7 M/s.
I believe those are the two fastest piston speeds in a road car.
My understanding is high performance street engines generally run at 20-25 m/s, Formula 1 over 25 m/s and fuel dragsters up to 30 m/s.
Our C30A has a piston speed of 20.8 m/s at 8000 rpm which is conservative and why our engines are lasting so long.
Assuming Honda has built in their usual safety factors in the C30 block and reciprocating mass perhaps we can consider a C30 engine could run at S2000 piston speeds, say 25 m/s.
At 25 m/s a C30 would be revving at 9600 rpm.
So a high revving C30 should be mechanically possible but some questions remain.
Are the oem pistons/rods/crank able to handle the inertial loads at 25 m/s with reliability?
One of the engine experts on the forum may be able to answer that.
Perhaps the next most important factor in a high revving C30 would be getting the air fuel mixture into the cylinders.
I believe Jon Martin was the builder of the first 3.8L C30 and I remember him telling me at an NSXPO the biggest problem making power in the 3.8L was the air fuel flow rates.
Others on the forum have spoken of the bottleneck of the C30 intake/valves/heads.
So if the C30 reciprocals are capable of turning say 9500 rpm the engine may be fuel starved and never get there.
Perhaps other Prime members have done work on this and can teach us more on the subject.
Failing that there is a lot of info on the web to read about rev limits and head flow rates so perhaps you can research that and share it with the rest of us.
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At a minimum, you're looking at pistons, rods, some mild head work, valves, springs, and a different intake manifold and throttle body. 9K shouldn't be an issue and with the above modifications, a bit over 9 could work, but if you look at stock dyno graphs, the NSX starts to choke after 7-7.5K RPM.
If you are in Japan, there are several shops who can help you. I would contact KSP Engineering or Spoon Sports. The JGTC C35 engines turned 9,000+. Like Billy said, you will need a revised bottom end, head work, ITB and a stand alone ECU. Toda Spec C cams, billet oil gear and kevlar timing belt too. You're really talking about a full race engine. Btw, building a C30A to this level will easily cost you $25k. But, it is possible. Like my dad always told me, speed costs money- how fast do you want to go? 
I am already designing such an engine for my forced induction setup. Although rpm (R)uins-(P)eoples-(M)otors, a good lifespan can be achieved if the engine is built with rpm in mind. Cylinder head modifications, bore size, a decent cam, and a good intake manifold will change the powerband and allow the engine to displace more airflow up top and achieve more hp. 9500-10k will be my sweet spot for my engine.
shawn110975
Suspended
My stock engine revs high enough for me, what will getting to the 9 or 10 really so for you? you gonna rev it at stop lights when girls walk by?
are you gonna be a 9.5K rpm in a turn?
do you wanna better DRIFT car?
goodluck in your quest take pics for us.
are you gonna be a 9.5K rpm in a turn?
do you wanna better DRIFT car?
goodluck in your quest take pics for us.
You probably don't need cams to run that rpm. Cams will be even harder on the valve springs. You can probably turn a stock motor to 9 occasionally but with some headwork/springs, 9 should be fairly reliable.
I am just thinking out a plan of action. The Mugen MF308 V8 is built for 16,000rpms. Now of course I know My little C30 v6 is no Mugen race engine, but I would think it would not be a stretch to achieve 10,000rpms mabe a little more with the right parts and work. I have talked to Spoon and they wont even consider such a build as they dont have the parts to build it and said I cant afford what custom would cost. As pissed off as i wanted to be for being judged on the spot to not have that kind of money I just agreed and left. I know what Spoon costs for little custom work so I didnt argue at all. Mugen does not do alot of custom stuff anymore except for its race cars so they are out. And KSP and Revolution dont do high rpm builds only bigger displacement like their signature 3.5L running Toda cams and In house ITB's that pushes 400hp. But I dont have the Almost $40,000 for that build and have always loved the sound of the MF308 and wanted to get that sound and response. Call me crazy if you want but I sold my 450hp R32gtr to get my nsx and I dont want to go back Turbo or supercharger. I want to stick with NA. I was just thinking about it as a possibility that would not be to out of reach.
In a high rpm situation one of my biggest concerns is the oiling system. I'd start looking at a proper dry sump setup for fear of even a Toda billet oil gear (what I have) exploding.
i love an NA build, especially for the NSX, but every time I get the itch and start researching I get heartburn. The thing is...even if you get all the parts its the engine builder that could easily make or break the situation.
i love an NA build, especially for the NSX, but every time I get the itch and start researching I get heartburn
. The thing is...even if you get all the parts its the engine builder that could easily make or break the situation.
Do you know why Mugen V8 is able rev to 16 K rpm?
Why do you want to rev to 10K rpm?
Is there some power level you want to produce that only revving to 10K will produce?
Share your math with us.
Btw... I'm not a professional badass driver like Billy but I prefer a broad powerband than a high revving peaky NA motor. It's just easier to drive. It's like the AP1 vs AP2 conversation. I'm the same about motorcycles too. I hardly get the most out of a 14k rpm in a CBR but I use the low end torque in a twin Ducati all the time.
Buy a mustang 
Or apparently a Z07!!! HahaBuy a mustang
I hope you are joking. There are some engine 101 books on amazon you can buy and read so you can better understand the basics of a high performance engine.
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Is this the same logic people used back when the typical v6 didn't rev to the 8k limit nsxs do? Why rev it to 8 it's too high!!! Are the people making these ridiculous comments not understand that engines need to move air to produce power?
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Cams are harder on the valve springs yes, which is why there are stiffer springs that are pretty much status quo when running a larger cam. Industry standard. To rev to 9k just raise the limit. To make power to 9500 and above takes a longer duration cam profile and supporting mods to the engine/cylinder head along with it.
Ok sorry about the late replay being in japan in a different time zone makes my time i see this later. I have been researching this alot lately and from what i have learned from a couple race shops and race teams and Mugen itself. They have all told me pretty much the same thing. The reason the mugen V8 was able to rev so high was mainly from its light weight internals, short stroke high lift cams better fueling and perfect micro polishing balancing and of course serious head porting. Another thing is ITB route is a must and using the shortest horns possible. As im sure you have read before, long horns increase engine Torque while short Horns allow more mass air in at one time for better high rpm power band. Like i said before from everything ive read and found out the 2 ways to make more power is to force more air and fuel in the combustion chamber and compress it. The second way is it suck more air and fuel into the combustion chamber and then compress it before ignition.
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I know that theres not alot piston, crank and rod options to be able to build a short stroke engine that would be needed to handle the kind of speeds needed.
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A high rpm high response engine Is ideal for track and light weight cars. The Higher the rpms the more air and fuel are being forced into the engine. Now like some have said your limited to the max your cams. valves and intake can allow in. NA reaspone is mmmm hmmmm
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I know that theres not alot piston, crank and rod options to be able to build a short stroke engine that would be needed to handle the kind of speeds needed.
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A high rpm high response engine Is ideal for track and light weight cars. The Higher the rpms the more air and fuel are being forced into the engine. Now like some have said your limited to the max your cams. valves and intake can allow in. NA reaspone is mmmm hmmmm
A small point but engines don't suck in anything.
The fuel air mixture is pushed into an engine by atmospheric pressure to fill the partial vacuum created by downward piston movement.
You could do the math on the stresses on the internals at 10 k rpm and compare that to the oem part specifications. It's possible Honda engineered in enough safety margin to use the oem parts at higher rpm. Could you do the calculations and let us all know how it turns out?
Not sure what you mean here?
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NA Response is overrated. All the top Prototype and now F1 cars run turbos.
But not because the drivers prefer them. If you asked F1 drivers what's more fun to drive: a naturally-aspirated 3.5L V-12 or a 1.6L turbo, I bet they'd choose the n/a engine all day long.
what's the weight delta between those 2?
the rules require them to run turbo....its sounds just awful flat compare to the NA V8/V10/V12....music to the ear and moves the soul.
Good discussion. An engine is really just an air pump. The faster you spin it, the more air you can move through it in a given amount of time (assuming the internals support that flow level). This allows the engine to do more work over time, which is another way to describe horsepower. A good example is NASCAR, where they put restrictor plates on the carburetor, which physically makes the barrel opening smaller. Less air results in less power. F1 chooses to manage it through rev limits. Again, they are restricting the amount of air that moves through the engine. I have no doubt a C30A can be built to efficiently make power at 10,000 rpm. My point to the OP is that this will be just as expensive if not more than a turbo solution. If max power is the goal, then I would choose turbo. If max NA power is the goal, then really the 3.5L builds are the best idea. Keeping the engine at 3.0L and spinning it faster will be very expensive, as you will need custom lightweight and perfectly balanced rotating assembly, bigger water cooling system, oil cooling system. The engine will make exponentially more heat at 10,000 compared to 8,000. You also may need to increase the flow rate of the heads and valvetrain to make sure it can handle the extra 2,000 revs. Probably why not even KSP or Spoon is willing to do it. Just looking at the list above, you're talking about a fully built race engine. That's $25k+ to do it right.
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