Engine re-building for high rpm 4

[BrianGar]

Hello guys, pretty wide range question, but has anyone on here been directly involved with taking standard inline 4 bottom ends and re-building them for higher rpm? Someone involved in days gone by with the BTCC(cars were 2.0L 16v and made 300 odd hp n/a) perhaps, or other.

A few pointers as to what Im aiming to find more details on,

Possible fitting of crank ladder style girdles to prevent cap walk.

Adjustment, or complete new choice of cranks.

Cylinder bore wall stabilisation using either sleeves, or by grout filling part way up the water jackets.

Bearing choice,

Con-rod choice,possible pinning of big end caps, and treatments>(could get involved so skip if needs be),

Piston choice, skirt treatments, ring details,

Possible reduction in size of journals to reduce friction, /surface speeds although I know most exists at the rings.

Block in question is a cast iron European block, Inline 4, not lined, two bolts just per crank cap.

Factory limited at around 7000rpm,

Looking to up that by 2000rpm and get it to last for more than 2000 miles on the track.

I have A LOT of studies done, but I just wanting to hear others views, and not really looking for a do this do that list. Just whatever comes into your head that maybe overlooked.

Thanks in advance,

Brian,

 

[TDIMeister]

When we scale down to motorcycle engines, >150 HP/L are fairly routine. By the key is, and my point was, that they still obey the BMEP and MPS limits I described above.

 

[yoshimitsuspeed]

The Forumula Atlantic 4AGEs put out over 240 hp.
That's pretty impressive for a little 1.6 liter but like evelrod said those motors cost alotta money.
9000 doesn't seem like a high mark to me but that may be because of the engines I am more familiar with.
Like people have said what needs to be modified completely depends on the engine.
A 4AGE of any generation could be made to spin to 9k with very little effort or modification though though the earlier 16 valves wouldn't make any power up there without some work.

 

[evelrod]

Without a doubt, the 4AGE is a good engine. The Cosworth BDA that it replaced was the engine I saw at 250hp, some years ago.
9000 is just a number...my little Mini is limited to 7800 simply because I want it to live longer than just one race. Our Lotus twink is limited to 8800 for the same reasons even though it should be "safe" to 12000...back in the 80's I came in with the telltale stuck at 10500 (the max) and the engine seemed fine.

Now, what IS impressive is watching a NASCAR V8 holding 9800rpm for hours on end, 500miles plus qualifying and testing...Unbelievable!
Sure, F-1's can pull 20,000 at probably a million bucks each...but a cast iron, flat tappet cammed pushrod American V8 with a single four barrel?

Rod

 

[BrianPetersen]

The RPM can't be considered in isolation from the stroke.

Friend of mine has a Yamaha FZR250 4-cylinder 4-stroke motorcycle, 249cc, with a nominal 19,000 rpm redline. But, the bore and stroke are only 48.0 x 34.5 mm, and if you work it out, the mean piston speed is only 21.85 m/s at that speed, which is well within the normal range.

15 bar BMEP for a normally-aspirated spark-ignition four-stroke engine running on normal unleaded pump gasoline is in a realm that is difficult to achieve.

For an American Nascar V8, no doubt the stroke is somewhere near 3 inches, I'm not sure of the bore and stroke that they are using in Nascar (I don't follow it). If it's 3 inches then 9800 rpm = 4900 feet per minute = approx 25 metres per second. That's near the upper limit of what's normally seen. The remarkable thing in that case is that the pushrod valve mechanism survives and the air going through the two-valve head can keep up with this.

 

[TDIMeister]

Brian:

http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm

 

[evelrod]

in the line of "leaving no technology untapped"...I present the current "state of the art" with antiqueated Mini engines in search of the magic "horsepower"...

http://www.swiftune.com/NewsArticle...stunningly-smooth,-high-revving-a-series.aspx

http://www.turbominis.co.uk/forums/attachments/402781-1.jpg

Rod