2021 Caterham CSR "CatKong"

[fastg]

I don't think your comparison to F1 engines is valid. There run very short stroke turbo engines and there piston speed is limited by an RPM and fuel flow limit, not piston destruction.  

 

This is an endurance spec motor, I know the owner 

 

 

Now lets return to "CatKong". 

 

Graham 

[Driverscar]

look back to the real Engins in V10 and V8 era. Its all about the Pistonspeed and explosion/burntime by NA engines.
"I know the owner" is the same like "my tuner said..."

 

there is only one:  Maths and Physics Everything else I assign to fairy tales or people have simply learnt the wrong thing.

Our Duratec is on the limit over 24-25m/s.

If we constantly go on the limit on Street or Track, we have to change Piston Rings and hone the cylinder every two Seasons.

 

I have seen some Duratec with bright polished cylinders. either because they were spun too high and /or bad piston rings and pistons from Supertech were used.

If you want to push the limits, I can only recommend using Mahle Motorsport or Cosworth pistons.

 

But because i love revs and their noise, i want to build a special engine, like the one that could have been used in the DTM in 1992, but has the durability of a Porsche 991 GT3RS.

[Croc]

On 6/2/2023 at 6:08 AM, Driverscar said:

For me, the 100mm Crank is way to unsporty. Its not about the quality of the Crank, but the Piston speed.
Rev. Limit is 7500RPM, instead of 8150RPM by the 94mm Crank.

 

 

I read through your posts and I do agree with a lot of your logic but there are other factors you do not mention - it was a compromise in the end.  

 

Bear with my explanation as I did not make a crank decision on the engine and have everything else be decided from that.  We started with stated objectives of what we wanted the engine to be and then come at it logically.  Crankshaft was a fairly early decision but not the first.   

 

During the planning stage for this project, we tried to identify the 'sweet spot' between engine displacement (2.3 vs 2.4 vs 2.5), the stroke and where we thought the power/torque curves would end up relative to the revs needed for the end objective.  The core of the debate was the 2.4L Duratec with a higher rev compared with the 2.5L with lower revs - which was best?  

 

A number of UK engine builders and one German race team believe the 2.4L Duratec approach is the right one - essentially validating your observations. 

 

Some of the open prototype classes that run the Duratec in the US favor the 2.5L approach. 

 

The displacement decision was a major determinant of end crankshaft spec.  I wanted bulk power/torque but also wanted durability as I am not planning to rebuild this engine each month.  Lower revs is consistent with durability objective.

 

A lot of the difference in the thinking for a final decision came down to the circuits where the car is running, gearing options and durability objectives.  

 

In the end we took the 2.5L approach.  This allows us to maximize torque.  On the circuits the car is likely to be running and the gearing selected (to provide the best compromise for the tracks) the max revs will be 7800rpm.  In reality I will never get that high.  Optimal gear change point is 7300rpm.  We achieved our engine objective with a 7500rpm limit.  For the majority of the tracks the car will be expected to run, a torque bias in the engine focus will be a big advantage.   Another advantage of this approach is lower revs lengthened the expected refresh cycle for the engine - so cheaper for me in the long run.  Given this is not a class race car, these are all acceptable compromises.  

 

If I was a professional race team, my decision would be different.  I would want a higher rev band and limit.  But I don't have a major sponsor allowing rebuilds once or twice or more a year.  So I am happy with my approach as it is a reasonable compromise and I don't think I give much away in terms of end performance.  As it is I think I am going to be at the limits of a CSR chassis so any more engine performance would just be wasted.  A torque focused engine will be easier to drive in that context.

 

I agree with you on choice of pistons and quality of internals.  My engine will not have the internals of a standard Ford Focus or Ford Ranger!  Being cheap on quality parts just comes back to burn you in the end.  

 

 

[Driverscar]

I can understand everything.
I am also just a hobby driver. Since we do a lot of hillclimbing and I grew up with four-cylinder engines that rev beyond 9000 and are designed for it, I feel more emotionally attached to the 2.4 engines and my 2.3 is an untouched 255hp Cosworth Standard engine. For me, on the road, it's more about the fun than the engine having 10hp more or less.

[John B]

I'm excited for you Croc. Time to awaken the beast!!

[Croc]

21 hours ago, Driverscar said:

I can understand everything.
I am also just a hobby driver. Since we do a lot of hillclimbing and I grew up with four-cylinder engines that rev beyond 9000 and are designed for it, I feel more emotionally attached to the 2.4 engines and my 2.3 is an untouched 255hp Cosworth Standard engine. For me, on the road, it's more about the fun than the engine having 10hp more or less.

 

I agree.  If I was doing this as a professional racing effort, I believe the 2.4L (with the 94mm crank) is superior because the higher rev limit achievable is more usable in a race environment.  Its just a very rare engine in the US racing community - probably as the race classes don't fit it that well, being focused around protoypes.  The Caterham racing here is either 420R or SCCA spec (Zetec engine - loosely approximating Sigma 150).  

[TurboWood]

Bringing to the top so Mike has to update us :)!

 

Daniel

[Croc]

Drivetrain is in now.   Oil line and coolant plumbing underway.   Integration (completing the wiring up) will be a bear.

 

 

 

Other than that I have been disconnected dealing with some distant family issues, traveling, plus the aftermath of my most expensive YouTube video ever - I spun a bearing on the BMW CSL. 

[wdb]

1 hour ago, Croc said:

Other than that I have been disconnected dealing with some distant family issues, traveling, plus the aftermath of my most expensive YouTube video ever - I spun a bearing on the BMW CSL. 

 

Eekazoids! Where is the car? I assume not at NJMP. Pretty chilly to be doing laps around these parts just now...

[John B]

Yikes on the spun bearing Croc!

But on the other hand, you could look at this as an opportunity. 

[TBone1209]

On 1/28/2024 at 12:26 PM, Croc said:

Other than that I have been disconnected dealing with some distant family issues, traveling, plus the aftermath of my most expensive YouTube video ever - I spun a bearing on the BMW CSL. 

Mike- I know we chatted briefly about it but don't remember the engine specs. Was it an M88? That could get expensive if so...

[CBuff]

I’m starting to think “catkong” is a mythical beast that doesn’t really exist.  

[JohnCh]

On 10/11/2020 at 1:56 AM, Croc said:

Once it was in Seattle in late 2019 the magic could begin.

 

Next time I'm at Beachman Racing, I'll try to remember to check the date codes on the tires and the FIA harnesses.  They might be knocking up against their expiration dates before the car is ready for its first track day     (And yes, I know I'm gonna pay for this...)

[Croc]

On 1/28/2024 at 5:15 PM, wdb said:

 

Eekazoids! Where is the car? I assume not at NJMP. Pretty chilly to be doing laps around these parts just now...

 

Yes its there at my garage right now on the lift - no engine in it.  No chance of doing laps as it is missing a key component.  The engine is in Redmond WA being rebuilt by a place that supports six race CSLs.    

 

 

13 hours ago, TBone1209 said:

Mike- I know we chatted briefly about it but don't remember the engine specs. Was it an M88? That could get expensive if so...

 

Oh its expensive alright.  I could rebuild many Duratecs or one Hasselgren Duratec for the same price.  But no, I have an M30 3.5L block with the 2 valve head (the 1970s version of the M90).  What you are thinking of is the M49 4 valve head (which is essentially a bolt on to the M30 block) which is $150K+ used assuming you can find one - unobtainium.  Would love one of those but the head alone equals the value of the rest of the car!

 

The M88 is the later road derivation of the M49 and is somewhat lot less inexpensive compared to the M49.  Easier to find and rebuild too - in relative terms compared with an M49.

 

I don't believe we got the M88 in the USA?  Was that in the M635 and M5 here?

 

Now, as USA7s has a member working at BMW, you would think he would be kind enough to casually drop an M49 in my letter box.  But nooooo....

 

 

 

6 hours ago, CBuff said:

I’m starting to think “catkong” is a mythical beast that doesn’t really exist.  

 

You may be right.  Fake news.

 

 

6 hours ago, JohnCh said:

 

...I'll try to remember to check the date codes on the tires and the FIA harnesses.  They might be knocking up against their expiration dates before the car is ready for its first track day     (And yes, I know I'm gonna pay for this...)

 

Fortunately, no belts in it from recollection.  Not even bought.  Same with the tires - wheels bought but no rubber purchased.  Now if I had, then yes they would have expired.

 

Luckily I have been making progress on other cars - Range Rover, Ferrari, Holden.  About to kill what remains of my wallet on Holden parts. 

 

When are you going to apologize to the masses for being the sole inventor of Mr Clippy?  Royalties must be excellent.....

 

 

[TBone1209]

On 4/2/2024 at 2:30 AM, Croc said:

The M88 is the later road derivation of the M49 and is somewhat lot less inexpensive compared to the M49.  Easier to find and rebuild too - in relative terms compared with an M49.

 

I don't believe we got the M88 in the USA?  Was that in the M635 and M5 here?

Yea, the M49 is unobtaniun unless you have connections and a huge wallet for sure. No I think you are right, the M88 was euro cars only. And of course the M1 ran it. At least you can get the M30 B35 parts and you can get them to make good power. Terry Tinney gets great results from them and they last... If you don't miss a gear 😉

[Croc]

9 hours ago, TBone1209 said:

Terry Tinney gets great results from them and they last... If you don't miss a gear 😉

 

Sadly he never returned my calls.  He was one of the rebuild options I called.  The cause was not over rev.  Most likely it is oil flow issues because the engine had piston squirters.  Oil seemed to not be dropping to the bottom end.  There was enough oil in the system so it seems it was a oil pump flow design problem which is yet to be fully understood.  Probably need an additional low pressure pump somewhere. 

[wdb]

6 hours ago, Croc said:

 

Sadly he never returned my calls.  He was one of the rebuild options I called.  The cause was not over rev.  Most likely it is oil flow issues because the engine had piston squirters.  Oil seemed to not be dropping to the bottom end.  There was enough oil in the system so it seems it was a oil pump flow design problem which is yet to be fully understood.  Probably need an additional low pressure pump somewhere. 

 

I'm being uncomfortably reminded of discussions surrounding the oiling system in my M96 (Porsche 996) engine...

[slowdude]

@Croc, sorry I don't follow this. Sent you a PM. Let's see what we can do.