4g64 / 4g61

[Freerevving]

What's the lifespan of the motors he's breathed fire into? What's the teardown and rebuild schedule? It's pure racing. It's a motor whose design is a decade newer that the DSM's.

what do you mean? that Engine's original production date was 1991, and most of those high-revving engines were originally produced by 1986 and 1987, they already redlined at 7400-8000 from the factory. The fact that they were either destroked or otherwise made to SAFELY rev up to and over 10k is not anything amazing... just not anything you are used to seeing.

Oil pressure needs to be high with these engines, the engine need to be perfectly balanced when it's built.
You have to check your lifter height every 30k miles (and possible shim them)... much much sooner if you've been racing.

And a lot of these engines are built for fun... the only ones I've heard of "catostrophic failure" were strokers, 2.1's and 2.2's.

When you set out to design a really high revving engine start with a head that has more valve area per cylinder displacement than the 4G63. But then it wouldn't be a DSM any more.

You have made the best point so far. Maybe (with the turbo) we are reaching maximum flow...
But I have a hard time believing that, since our heads are designed much better than, and have larger valves than the VW heads... dare I say they're designed better than most Honda heads?...
But they don't have turbo's and we do. I could see where adding larger valves, maybe even 2mm over would help in this situation.

But I know there are people out there pumping out 800 hp on DSM heads.
at least 1/2 of that should be easily acheivable from a high-revving standpoint.
The engines you see now successfully churning out high revs and high power do not alway have enormous ports. In fact, we do.

I'm sure we have what it takes to effectively move the valve train at those revolutions... we just don't have the need. Sure, you begin to lose volumetric effeciency at those speeds, but so does increasing the displacement... that's why racing usually opts for more cylinders. After all, an engine is best realized as an air pump.... you can either speed it up, make it bigger, turbocharge it, supercharge it, or a combination of those. Hell, VW now offers a 1.4L supercharged AND turbocharged (in series) engine that revs to 9000. for some of the European models.

In the the link you provided he has done some calculations... Almost the exact same thing was being said about the 9A and PL heads, that they were reaching their physical limits to pump air... loooong before 9500 rpm... ALL the naysayers were proved wrong with some dyno charts. Some engines producing 110hp end up with 250whp at @ 9900 (I'll admit some of these were more expensive engines)... Most of the budget engines had PL and 9A heads were made to rev to 9500 sometimes higher... on a budget they were safely producing 240 hp (at above 9k) up from their original 125-135hp... Some of the smaller engines were known to have 270hp (that's up from 110hp) but were made/priced for racing. These are all the higher numbers, it was most common to see someone churn out 200-230whp from a high revving ITB'd 2L/1.8L engine on a budget. There were some amazing 1.4's but I think the 1.6 and 1.8 cranks had the best stroke for the most power.

These guys were usually either American or English (PoloV8 was both) and they proved a lot of people wrong locally. All they were doing was what has been popular in Europe (especially Germany): People doing it without any real scientific backround/knowledge and finding out that it works.

 

[Freerevving]

I see now why Defiant moved this to the Hangout.. this is more of a "Coate's" subject for most people...

I guess I take it a little more seriously than most

eBay Motors: JDM MITSUBISHI 4G61 T ENGINE FWD 5 SPEED MANUAL LSD TRA (item 180282160242 end time Sep-02-08 08:56:07 PDT)

4G61T

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[bastarddsm]

get er done there hot rod, when you find that it is far more productive to build a motor that makes power to about 9000, be sure to come back and tell us.



Make sure you patent you magical lifters that keep the rockers from moving in an arc...... or your guides that allow .700 lift.
I'm sure your stock springs will take a 288* cam if its only got .100" of lift with no sweat. Throw somthing in there with some lift and your valves will float by 7000 just like everyone else.


Also what did you do to your tranny to make it shift at 12K+. Surely you could put all the major tranny rebuilders outa business with this technology.

 

[Freerevving]

get er done there hot rod, when you find that it is far more productive to build a motor that makes power to about 9000, be sure to come back and tell us.



Make sure you patent you magical lifters that keep the rockers from moving in an arc...... or your guides that allow .700 lift.
I'm sure your stock springs will take a 288* cam if its only got .100" of lift with no sweat. Throw somthing in there with some lift and your valves will float by 7000 just like everyone else.


Also what did you do to your tranny to make it shift at 12K+. Surely you could put all the major tranny rebuilders outa business with this technology.

Please tell me where you found anything like this in my text.

I suspect you would only need .470" of lift as we are already running to 9000.. No scratch that.. You could just use your GSC2's or 288's to have a 10k redline... 10k is in the block not the head...

I said over and over again that a high-revving turbo engine is not necessary... I am not doing this. I might if I had nothing better to do. Originally I thought I was helping someone to do this, instead of entertaining an idea. I guess I didn't read close enough JUST LIKE YOU. And besides, you say 9000rpm? It's only productive for me to make an engine that redlines below 8k. My GSX doesn't live at the track.

A lot of people around here are compelled to be against something... and come up with rediculous ideas for why it "just won't work"... Does it make you feel cool? to be against something for no good reason? (Oh no Defiant, please refrain). The head is by far not the biggest obstacle...

...and you guys with knowledge don't realize that the only thing really holding anyone back from going to 10k is the rod ratio. The stroke is just a little too large to be safe. This could be compensated with longer rods and shorter pistons, but is best remedied by a taller block, longer rods, and shorter stroke.

Our guides (with seals) are supposed to allow 19mm of space... The most you would need for 10k is 13mm... not even that, 12.5mm would be plenty

And PLEASE show me some evidence of valve float.... especially some bent valves, damaged pistons, Screwed up dyno charts ANYTHING.

Too many people are decided that this couldn't work, before they even have a good reason why.... Then they take the time to post, only to make a weak argument of why the head isn't capable of it. I've seen it done with a lot more primitive heads... and we are already pushing 9k... we are fortunate that our heads are more capable than the rest of the engine.

If one wants to criticize or to point out the problems to be encountered in building this, they certainly shouldn't be focusing on the head. I'm suprised no one has mentioned anything about rod ratio, block height, pistons, rod length, piston velocity, etc etc... That part is still somewhat a mystery to me, and could quite possibly prove to have a problem.

Also what did you do to your tranny to make it shift at 12K+. Surely you could put all the major tranny rebuilders outa business with this technology.

Oh you want to know my secret? I put in "Top-Secret Space Goo"... it's new on the market... it allows my transmission to shift at 18k rpm... oh wait, I mean 21k rpm....... Maybe if you pull that GL5 out of your transmission you'll be able to shift above 7k... but your gears are probably toast by now

wow 16's seconds isn't that what a Cavalier runs stock?

 

[bastarddsm]

Please tell me where you found anything like this in my text.

I suspect you would only need .420" of lift as we are already running to 9000.. No scratch that.. You could just use your GSC2's or 288's to have a 10k redline... 10k is in the block not the head...

I said over and over again that a high-revving turbo engine is not necessary... I am not doing this. I might if I had nothing better to do. Originally I thought I was helping someone to do this, instead of entertaining an idea. I guess I didn't read close enough JUST LIKE YOU. And besides, you say 9000rpm? It's only productive for me to make an engine that redlines below 8k. My GSX doesn't live at the track.

A lot of people around here are compelled to be against something... and come up with rediculous ideas for why it "just won't work"... Does it make you feel cool? to be against something for no good reason? (Oh no Defiant, please refrain). The head is by far not the biggest obstacle...

...and you guys with knowledge don't realize that the only thing really holding anyone back from going to 10k is the rod ratio. The stroke is just a little too large to be safe. This could be compensated with longer rods and shorter pistons, but is best remedied by a taller block, longer rods, and shorter stroke.

Our guides (with seals) are supposed to allow 19mm of space... The most you would need for 10k is 13mm... not even that, 12.5mm would be plenty

And PLEASE show me some evidence of valve float.... especially some bent valves, damaged pistons, Screwed up dyno charts ANYTHING.

Too many people are decided that this couldn't work, before they even have a good reason why.... Then they take the time to post, only to make a weak argument of why the head isn't capable of it. I've seen it done with a lot more primitive heads... and we are already pushing 9k... we are fortunate that our heads are more capable than the rest of the engine.

If one wants to criticize or to point out the problems to be encountered in building this, they certainly shouldn't be focusing on the head. I'm suprised no one has mentioned anything about rod ratio, block height, pistons, rod length, piston velocity, etc etc... That part is still somewhat a mystery to me, and could quite possibly prove to have a problem.



Oh you want to know my secret? I put in "Top-Secret Space Goo"... it's new on the market... it allows my transmission to shift at 18k rpm... oh wait, I mean 21k rpm....... Maybe if you pull that GL5 out of your transmission you'll be able to shift above 7k... but your gears are probably toast by now

wow 16's seconds isn't that what a Cavalier runs stock?

The lower end is not a problem. With the short stroke 1.6/8 crank and some custom long length rods in a 4g64 block, there would be no problem at all. There is no magic number for an rpm that a particular rod stroke ratio will survive. Granted an engine with a smaller r/s ratio will wear faster, but any high rpm engine is a high mainance engine, so this is really of no concern.

The HEAD is the problem, it will not flow enough air to make any decent power above 10k.

I'm not sure what your smoking but your not gonna make power above 10k with only .420" of lift. Sure you can wind it that high but the power will fall off drasticly.

I'm not sure if you have ever flowed a 4g63 head, but they do flow very well up into the .700" lift.

To make power at these high rpm levels, huge lift and lots of duration are needed. Our heads cannon support these numbers.

It's also well known that to be able to shift consistanly at 10k+ double synchro gearsets as well as a 7.25 double disk clutch is needed.

If you look at the big guys, you quickly see that no power is made at high rpms, otherwise they'd be doing it. The horsepower gains would be tremendous, if our heads could support a torque peak of 10K. We would probably see 1500hp out of a 4g63.

I'm not going on a whim, I'm going on the fact that our valvtrain geometry cannot support the cam profiles required to make power at 10k+.

Talk to turboglenn about valve float with stock springs and hks 272 and 264's

Also can you shed light as to how my posted time slip is relevent to this discussion.

 

[delta448]

75mm stroke with off-the-shelf 162mm magnus rods = 2.16 rod ratio
10,000rpms = pistons traveling at 12.5 meters per second (average for a 75mm stroke)

I don't think the bottom end surpasses the valvetrain in deficiency.

 

[Freerevving]

75mm stroke with off-the-shelf 162mm magnus rods = 2.16 rod ratio
10,000rpms = pistons traveling at 12.5 meters per second (average for a 75mm stroke)

I don't think the bottom end surpasses the valvetrain in deficiency.

???? 75mm stroke????
I believe the same thing about a 75mm stroke... But the 4g63 has an 88mm stroke and the bottom end is too deficient at 10k

I'm not sure what your smoking but your not gonna make power above 10k with only .420" of lift. Sure you can wind it that high but the power will fall off drasticly.

sorry that was a typo, .470", thanks for pointing that out

The lower end is not a problem.

So you think it's safe to constantly rev a 2L beyond 9000? I don't think it's safe to rev it to 9000. The lower end is indeed a problem, unless you go with a shorter stroke.

There is no magic number for an rpm that a particular rod stroke ratio will survive.

No... But mathematically our rod ratio is "safe" to about 8200 on a perfectly balanced engine... higher with forged materials

You really ought to read up: http://www.strokerengine.com/RodStroke2.html

The HEAD is the problem, it will not flow enough air to make any decent power above 10k.

and then you say:

I'm not sure if you have ever flowed a 4g63 head, but they do flow very well up into the .700" lift.

Okay thanks for proving yourself wrong, that should be good for 16k rpm...

And where do you get your information from?...

the whole point to shifting at 10k would be when your power begins to fall off before that. You DON'T want to shift at peak hp.

.700" lift? that's almost 18mm lift! I've never even HEARD of a camshaft with that kind of profile! rofl... yet there are many people (with lesser heads, mind you) shifting at 10 and 11k! Why? Because the lower half is not "working against itself"..... damn .470" is enough. Hmm maybe .500 would be nice

Is this one of your "rockers moving in an arc" theories?

some of the guys shifting at 9000 are "still making power"... in actuality they're making peak power probably at around 8.5k... but with a 2000 rpm drop between gears, if they didn't take the risk of severe damage to their engine they would be shifting above 9000!
http://www.dsmtuners.com/forums/ven...-english-racing-show-drag-42r-beast-dyno.html

wow this guy had a pretty good shift at 7500 WITH HKS 264's!!! the camshaft king of Low Rpm's!!!! I wonder what kind of cam you'd need for 2000 more rpm?

woudn't take much

While I admit it would be best to find a larger cam than 288*-- please remember, before responding, that you won't ever need more than .500" lift, longer duration will do--
and one would definitely need to upgrade their valvetrain (stock won't do)... a 288* cam can definitely take you above 9000k even though it would be ideal to find something larger...

To put it simply, a spring & retainer change will have our heads doing 10k rpms, while our pistons would be scuffing the crap out of the cylinder walls until catastrophic failure at both the crank and rods

 

[TunaTalon]

To put it simply, a spring & retainer change will have our heads doing 10k rpms, while our pistons would be scuffing the crap out of the cylinder walls until catastrophic failure at both the crank and rods

Forces on the pistons and rods are a strong function of weight. Changing out those stocker rods and pistons on a 7 bolt to Wiseco and Eagle will reduce the forces at 10,000 RPM to the same value as the stock 2.0L at 9,000 RPM.

With the Eagle/Wiseco combination the side loading friction at 10,000 RPM is about equal to the stocker at 9,600.

But to what avail? At 10,000 RPM the flow through the 4G64's valves is over .6 mach and experiencing sonic chocking.

More boost will not increase the flow velocity through the valves at 10,000 RPM where they are sonic chocked. More boost will make more power because the same velocity has a higher mass flow rate.

 

[Freerevving]

Yes I agree completely about the block... weight plays the largest role since oil and bearings have their limits... and like you said, strength plays a large role too... stock internals are not adequate to handle 9000 rpm on a 4g63... even forged and balanced internals can be taking risks at that rate, but the real risk is when the force (from hp) is increased.

As far as sonic choking goes... There are too many variables for one to decide that the air speed is mach 0.6, or that mach 0.6 makes high revolutions pointless... some of these variables are displacement, air density and/or boost, valve lift and duration, etc. I think neither you nor I have any idea about the air velocity on a 4g64 at 9 or 10k rpm. Besides, we are talking about a 4g63 head. Sonic choking has not greatly affected others who are succesfully revving to 11k with heads that flow much less than ours. If it does play a role, then it must not be an obstacle

If rpm plays such a big role in maximum air speed, then explain how there are so many automobiles revving to 10, 11, and 12k rpm... A street bike can do it and it developes 180-200hp, with similar displacement to a 1.6/1.75 liter frankenstein.

I think a good comparison, for anybody who "magically" doubts the 4g63 head, is to take a look at the limitations with a 4 cyl street bike... with their small valves and ports, they can pull 12k rpm because of their excellent rod ratio and smaller displacement... the same concept as a destroker.

 

[delta448]

???? 75mm stroke????
I believe the same thing about a 75mm stroke... But the 4g63 has an 88mm stroke and the bottom end is too deficient at 10k

From the first post of the thread:

Ok, lets say someone is totally bored and has a lot of money they don't mind wasting. Would they be able to put the 4G61 crank into a 4G64 block with out trouble?

The 4G61 crankshaft has a 75mm stroke. The engine we are discussing in this thread is the hypothetical 4G61 crank in a 4G64 block, and the possibility of a destroked 1.8L 4G64, not the standard 88mm 4G63 crankshaft. If we were talking about a stock stroke 4G63, then yes the block is obviously lacking.

If rpm plays such a big role in maximum air speed, then explain how there are so many automobiles revving to 10, 11, and 12k rpm... A street bike can do it and it developes 180-200hp, with similar displacement to a 1.6/1.75 liter frankenstein.

I think a good comparison, for anybody who "magically" doubts the 4g63 head, is to take a look at the limitations with a 4 cyl street bike... with their small valves and ports, they can pull 12k rpm because of their excellent rod ratio and smaller displacement... the same concept as a destroker.

The head would be fine for 200HP at 12k rpm on smaller displacement if the valves wouldn't float, but the point is that a measly 200HP can be made much more easily and at a much lower (safer) rpm on the proposed engine geometry.

There would be sonic choking only when that maximum level of airflow is reached, not when a certain rpm level is reached. The whole argument is not about making power at high rpms, it's about increasing the limit of the power by expanding the operable engine rpm range. If you reach the maximum sonic airflow at 8k rpms, revving it out to 12-14k is completely pointless. The head limits the destroked engine both by it's inability to handle high rpms without float and by not having sufficiently sized air passages to increase max power above the normal limit, which granted... is quite high. What HP is Shep's car up to now?

I think what I'm trying to say is, there's a point (admittedly very high up) where it isn't useful to rev any higher. Unless you're using a ridiculously massive turbo you don't need to hit 12k+ rpms to utilize it's flow and efficiency.

Once you hit the airflow limit of the head with the massive turbo at less than your max boost capability, you'll be slower than the next guy who's turbo gets him exactly to the sonic airflow limit at max boost at lower redline rpm and has a much faster spool.

 

[Freerevving]

From the first post of the thread:

The 4G61 crankshaft has a 75mm stroke. The engine we are discussing in this thread is the hypothetical 4G61 crank in a 4G64 block, and the possibility of a destroked 1.8L 4G64, not the standard 88mm 4G63 crankshaft. If we were talking about a stock stroke 4G63, then yes the block is obviously lacking.

The head would be fine for 200HP at 12k rpm on smaller displacement if the valves wouldn't float, but the point is that a measly 200HP can be made much more easily and at a much lower (safer) rpm on the proposed engine geometry.

There would be sonic choking only when that maximum level of airflow is reached, not when a certain rpm level is reached. The whole argument is not about making power at high rpms, it's about increasing the limit of the power by expanding the operable engine rpm range. If you reach the maximum sonic airflow at 8k rpms, revving it out to 12-14k is completely pointless. The head limits the destroked engine both by it's inability to handle high rpms without float and by not having sufficiently sized air passages to increase max power above the normal limit, which granted... is quite high. What HP is Shep's car up to now?
I think what I'm trying to say is, there's a point (admittedly very high up) where it isn't useful to rev any higher. Unless you're using a ridiculously massive turbo you don't need to hit 12k+ rpms to utilize it's flow and efficiency.

Once you hit the airflow limit of the head with the massive turbo at less than your max boost capability, you'll be slower than the next guy who's turbo gets him exactly to the sonic airflow limit at max boost at lower redline rpm and has a much faster spool.

Thank you, you seem to be in complete agreement with me...

You came in when others were arguing that the 2L block would be fine for 10k, while the head wouldn't...
and thank you, Shep's car is a good example that the limits are quite far on these heads.

I would like to point out that I never claimed (or even implied) that you would make more power with smaller displacement and higher rpm's, than more displacement with lower rpm's... I also pointed out, more than once, that it's almost pointless with a turbo, since we can just turn up the boost ...

But, contrary to what some believe, it's perfectly feasible to use the 4g63 head to make a high-revving turbocharged vehicle with a considerable amount of horsepower, and far from impossible. If someone wants to do it, there isn't much stopping them... as long as they destroke from 88mm and prepare the head.

thanks

 

[Freerevving]

Here's someone who made a 1.6L turbocharged engine, with a head that flows less than ours... they revved to 11000 rpm to generate 420hp (314kW)... just one way to do it without increasing displacement.

If you look at the dyno plot you can clearly see that he was sonically choked... NOT...

more proof that high rpm isn't going to make intake air hit "teminal velocity"
pay close attention to the second half of the video, where it shows his tachometer and then his dyno plot

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This stuff is nothing new.... but apparently new to some people on this forum... It helps to have a grasp of N/T technology...

 

[Stapl3]

Start out with the 4g *wide*block, and use a b2600 adapter to bolt on a RX7 transmission. Those <3 the revs from what I've experienced. You'd have to go RWD however, but fabbing mounts is fun and driving it would be even more fun.