Birth of the 2270 RS Roller Cammed Street Engine

Birth of the 2270 RS Roller Cammed Street Engine!

This has been a long time coming... Nearly 3 years since we started the roller camshaft program and prior to that two more years went into thought and cam profile development.
Today I threw Beth the keys to her "2270 RS" Powered MassIVe79 Vert and officially signed off on it's completion. All we have to add is the RAT direct fire and A/C compressor, but other than that the car is 100% completed.
Beth's Vert ran a 2.9 Liter twin plug monster last year,(making 250HP and 255 lb/ft of torque netting 195/206 at the rear wheels!) but the power was so extreme that the car could not be driven by her without serious risk of damage to the transaxle or vehicle or herself.
The "2270 RS" that took the place of the 2.9 has everything that we ever wanted, a ton of torque coupled to good, usable HP and better fuel economy than I had predicted. Most importantly this engine has a broad operating range with exceptional drive-ability and a torque curve that is unparalleled by anything I have ever designed or built before.
Having put 6K miles on the 2.9 last year and having driven the car with no other changes made about 350 miles thus far myself, I have to say that the car is much more fun to drive with this engine installed!! It may not be as fast and may not have as much torque, but what it does have is a great mix of RPM range and throttle response, and on top of that the power is even more crisp than with the much larger engine. With the 2270 RS the car is actually making more HP per liter and achieving the same or better MPG.
Now I'll share a bit about this engine's design... It won't be a lot because its our newest technology and it appears that we have someone who wants to play games with us that would love to know what makes an engine like this tick.
The goal was to create an engine with 4,000 RPM of usable power and to make peak HP at or below 6K RPM. All specs below are as the engine is set up currently after being optimized on the engine dyno and chassis dyno.
This is now a completely developed 2270 roller cammed offering for our turn key engine program.
Case- Built from an EA code 1.7. The case registers were decked and the engine received the standard RAT preparation work.
Crank- 78mm counterweighted
Rods- H beam @ 5.325 length
Cam- RAT 9905 roller profile netting .477 lift at the valve with an intake duration of 228*@ .050 (exhaust lift and duration not disclosed) This is a stock intake cam profile for a very popular roller cam engine that uses EFI.
Lifters- RAT "Big Wheel" rollers in Manganese Bronze bushings fitted to otherwise stock lifter bores
Cylinders and Pistons- LN Engineering Nickies in 96mm with JE forged pistons (these are used items from our R&D program that are 6 years old and have been used in 5 different engines!)
Deck Height- .031CR- 9.1:1
Cylinder Heads- RAT/ HAM LE 215 single plug with Level 2 springs designed for the roller cam. Len hand ported the exhaust port to alter the I/E ratio for this high torque engine that will be using an exceptionally small exhaust system primary tube diameter for such a large displacement. Len did an exceptional job with the heads as these are some of the highest velocity ports we have ever experienced![IMG]http://images.thesamba.com/vw/gallery/pix/553477.jpg[/IMG]
Exhaust System- Tangerine Racing EVO with 1.5" primaries and a twin outlet muffler custom built by Chris Foley for "The Super 2 Liter" project back in 2005
Induction- (NOS) Dual 40mm Dellorto Carburetors with 34mm venturis and 2-1/16 RAT "supervelocity" stacks. (Remember this is an odd combo, most of the time 40mm carburetors do not work well on a conventional 2270) SDS EFI will soon control fuel and spark for this engine, it was originally developed for EFI, hence the very mild roller cam.
Ignition- Mallory Unilite for the time being, will be changed to RAT DIS system ASAP! (This was an old Mallory that was our back up for the A.I.R. Racing 914)
Cooling system- RAT V2 DTM with Porsche Seal Gray base/clear paint detail (By me:-) oil cooling is handled by a single setrab fan pack external oil cooler.
Ancillaries- RAT/ Gilmore A/C System installed by Jeff Patterson of Autohaus. (compressor yet to be installed)
Transaxle- RAT Stage "B+" with super tall gearing in every position to best utilize the extreme torque of the engine.
Now lets go over some of the testing the engine went through on the RAT Engine Dyno, then I'll follow up with what we saw on our dynojet chassis dyno as well:(these are the most significant graphs, there are 20 more that aren't pictured)
Of course this is a 2270, my most favorite Type 4 displacement of all time. These engines generally like 44-45mm carbs best with a 36-38mm venturi. I started off the testing with a set of 45 Dells with 38 vents, but aborted that test due to the carbs needing some repairs from Art(I sent them to him and will have them back for chassis dyno testing tomorrow!). So I decided to go straight to our 48mm Dells with stock 40mm venturis installed.
Round 1: This began with default timing at 10/30 degrees with 48 Dells and a Tangerine 1-5/8" EVO header. We also had the engine set up with the cam timing "straight up" as a default. We did 3 runs to optimize timing and jetting before actually logging this run. Here are the results. Not bad for the first run!
[IMG]http://images.thesamba.com/vw/gallery/pix/553456.jpg[/IMG]
In round two I decided to retard the cam timing a bit to try to pick up some more top end power, since I wanted 180 HP... I made this change but nothing else.[IMG]http://images.thesamba.com/vw/gallery/pix/553457.jpg[/IMG]The engine didn't like this as it lost throttle response and also didn't make the numbers that I expected.
Then I decided to go 3 degrees advanced with the cam timing, here are the results[IMG]http://images.thesamba.com/vw/gallery/pix/553458.jpg[/IMG]This was more like it as the engine responded more quickly to throttle manipulation and it just plain ran better! It was making the broad power that I was looking for, but not enough of it.
The engine seemed to have "big carb syndrome" so I decided to throw my NOS 40 Dells on the engine that it would be ran with in Beth's car for the remainder of the test work.
In this graph I left the cam timing advanced 3 degrees and did nothing except bolt on the NOS 40 dells right out of the box. I left the 1-5/8" Tangerine Header so I would bnot create any variables. I fully expected the engine to lose 15HP as these engines normally do when going to a 40mm Carburetor on a conventional 2270. Here are the direct results after optimizing the jetting to the same AFR average we had with the 48s.[IMG]http://images.thesamba.com/vw/gallery/pix/553460.jpg[/IMG]
As you can see the engine did some funky things with the more limited intake flow, but it did not lose the HP I expected with the 40s!! This was great! Look at that torque starting to climb!!
Based on the graph comparisons and the engine's behavior under load I had a hypothesis that the exhaust system was now too large for the limited intake and was over scavenging, so we went ahead and installed the custom 1-1/2" header that Chris had made for us especially for the car. I was fully expecting a gain of low end torque and midrange throttle response, but I did not expect the HP to respond as it did!
In this run you'll see that the open header effected low speed performance and the graph is a bit bumpy[IMG]http://images.thesamba.com/vw/gallery/pix/553472.jpg[/IMG]
We would now test the engine with the two different EVO mufflers that Chris provided us with for the occasion. I started with the twin tip unit first, since it fits the car best and has the pissed off attitude out the tail pipe that I love! This is one of the first mufflers that Chris made several years ago, so it needs some modernization.[IMG]http://images.thesamba.com/vw/gallery/pix/553465.jpg[/IMG]
Here is the most recent muffler development from Tangerine Racing coupled to the engine. This is a single tip muffler that had the best all around performance and the best numbers as wel. The engine ran cooler temps with this than any other arrangement and it had a deep tone.here is the money shot![IMG]http://images.thesamba.com/vw/gallery/pix/553464.jpg[/IMG]LOOK AT THAT TORQUE!!! Its totally flat from 2K clear to 6K!!! Do you know how hard that is to do over a 4,000 RPM power band!! I have NEVER done this before and its impossible with a conventional camshaft arrangement IMHO especially starting at such a low RPM at WOT!!!
Look at those peak numbers!! 183 lb/ft of torque at 4K and 166HP at 5K with a nice stretch without much fall off to 6K!! This is exceptional for a 2270 with a 1.5" header and a set os super small 40mm carbs with 34mm venturis!!!! The most I have EVER gotten from a 2270 with 40s in the past is 145HP and we have never seen a 2270 that would even function with a 1.5" header, but this one made MORE power with the smaller header even when we didn't expect it!
Now here are the graphs from the engine as installed into the vehicle and tested on our Dynojet Chassis Dyno right here at Heaven. Note that I pulled I started the dyno run AT IDLE in 4th gear and stabbed the throttle for a pull clear to 6K!!! How many engines do you think can idle a pair of 5,000 RPM rollers in 4th gear and have the throttle stabbed to WOT and pull straight to 6K without stalling or bucking???? I haven't tested one yet that could, but this one can and LOVED it![IMG]http://images.thesamba.com/vw/gallery/pix/553388.jpg[/IMG][IMG]http://images.thesamba.com/vw/gallery/pix/553391.jpg[/IMG][IMG]http://images.thesamba.com/vw/gallery/pix/553390.jpg[/IMG]
All this goes to show the incredible power potential from the roller camshaft technology and how the change of camshaft technology totally alters what the engine will optimize with. This also illustrates that one cannot cloud development due to their own personal preferences or assumptions!! WE MUST try everything possible no matter what we think or why and previous experience can't be looked upon when moving forward.
Future developments:This is just the beginning for this engine. The car has now been fitted with A/C and will be driven 10K miles by the end of July. During this time I will test the engine with the 45 dells that were sent to Art to be gone through and we'll work with Tangerine Racing to further develop the twin tip muffler... Hell I might even give this one a shot of Nitrous, because I think it would LOVE it!
We will also be using this engine to do the final test work on the RAT DIS ignition system in conjunction with the A/C arrangement for a super clean engine bay thats functional.
In July this engine will receive a new "Dual Fuel" ECU that has never been ran in the US. It incorporates direct ignition and EFI into a package that is totally self learning in closed loop with sequential injection and dual O2 sensors as well as OBDII capabilities and its own functional "Check engine light" and data logging built right in.
In closing I could not be more happy with this version of the 2270. It runs quiet, smooth and has exceptional power at EVERY RPM while being very easy to drive! Remember, this engine can pull to 1,000 RPM @ WOT under full load and do so with carburetors even though it's cam is specifically configured for EFI!!! Wait till we install the EFI on the engine and see what that does!
The goal with this car has been quiet, smooth operation with exceptional drive ability and throttle response thats tame enough for Beth to drive every day with creature comforts like A/C. Reliability, performance and efficiency- Perfected.
I have news for ya... creating an engine like this takes more than "4 year" of development and a few left coast marginally developed, cookie cutter components... Making 125 lb/ft of torque at 1,000 RPM and spread it over an operating range of 4,000 RPM with peak numbers at less than 5,500 RPM is hard as HELL to do!! A HP seeker or drag racer will never even graps the mindset required to do this!
Here are some added pictures of the engine and the "front end" of the very sweet factory appearing A/C system that Jeff Patterson installed last week.
I am glad Beth loves driving this beast!!
How much more proof do you need that "Bigger is seldom better".... This engine replaced a 2.9 Twin Plug!Jake Raby
President, Raby Enterprises Inc