Performance of the CR 250 National Engine?

[Cameron]

I see Ian Harrison from Viper Engines in the UK is now a member of the Aus forum.
Welcome to the Forum.
If you read this post Ian would like to know if you could tell us what your national engines are capable of ie i hear they run on pump grade fuel and produce over 60HP?
Thanks
Cameron

[SAFE Evolutions]

Don't forget Cameron, dyno's are all different from one another. Unless you send yours to him (Ian), you will never really know how much more his have than yours.

I can tell you first hand that out of the box, A Viper CR 250 package has ample power even with 5 jet sizes too rich, the wrong gearing, a driver that hadn't driven for 15 months and he couldn't even sit in the seat properly. Not to mention, new but old hard type Dunlop tires.

Look on track against others packages. Check out natsoft from the last VIC Philip Island round, I think that says it all.

Regards
Scott

[nat 6]

Hey Cam it all depends on the engine is your engine crank or barrel inducted

[Cameron]

Was actually wanting to see what the engines in the UK are making etc as seems to be very large and competitive fields over there and Ian has obviously been a major player in supplying reliable fast engines. There is definitely a bit of life in Aus as well, this year seems to be the best from a national point of view in years.

[Charlie114]

Hi cameron. A good nat Cr250 engine runing on race spec pump fuel will produce around 62 to 64 BHP if you use
an engine carby and exhaust package from any of the top UK tuners regardless if it is barel or crank case inducted. Depending on which tuner you talk to some prefer the crank inducted motors and some prefer barrel inducted. The Man turning out the best engines at the moment is a chap called rob walkinshaw and he is based over in ireland. his engines have won the brithish champs recentley and are always amongst the top.
charges bit money but you get very good results.

[Cameron]

So somewhere in the low to mid 60's . Do the later Cr's have a closer ratio gearbox ? As a 5sp with a close ratio box would be on the heels of an inter on shorter circuits if that were the case.
Cameron

[Sam Zavaglia]

So somewhere in the low to mid 60's . Do the later Cr's have a closer ratio gearbox ? As a 5sp with a close ratio box would be on the heels of an inter on shorter circuits if that were the case.
Cameron

Cameron, your from QLD right?
I hope your not talking about front running twins or you will be in for a rude shock.......even 125's beat some of the slower twins both in lap times and to the chequered flag, long or short track. Didn't Russell Jamieson in his 125GB spank the field at Morgan Park all the time, all except for 1 or 2 twins.

Here is a QLD state title where both these well known twins got beat from a 125GB.  

[Cameron]

yep QLD where all it does is rain lately. Need to add a keel and be able to float at the moment to win any race.
So does anyone know if the later CR is a close ratio box? just curious.
Cameron

[nat 6]

no its not a close range gear box but you can change internal gears in them 

[Charlie114]

For the close ratio gearbox on a cr you are lookig at about $1000 for a good one.  the last one i had done we changed 2nd 3rd and 5th gear. Back in the UK we wher within 1 second of the top twins lap times at the hilly circuits. If your running on fairley flat tracks and don have much competition i would stick with a standard box until you have a good engine package or you wont really benefit form it.

[Viper Racing UK]

Hi Guys

Many thanks for the welcome from Cameron and all.

I will put the Aus forum in my favourites from now on and get back here as often as I can.

There is an awful lot of bull talked and misunderstanding regarding engine power. If anyone thinks that horespower alone wins races, they are sadly deluded.

In general, people chasing horsepower would be much better employed on working on their understanding and implementation of setup and balance of the chassis and on their driving techniques and ability.

Having said that you have to have a good engine as part of a successful package.

I would always put greatest credence on what the top drivers and teams have to say. They are the ones who know how to win and have the backup of lap times, race and championship victories to validate what they say.

I don't know of a tuner who ever claimed his motor won a race, but hopefully we can contribute.

The motor that Marty is running is the 2010 development of our successful crankcase induction CR250. This motor was used to win the MSA British F250 National Championship in 2007 and 2009 and the Super 4 (British short circuit Championship) in 2009. In points scored and race result terms, Viper Racing UK with this motor has been the most successful tuner in the UK over the last 3 years.

This motor can currently run on anything from 99 Octane pump fuel to MR8, C12 or Avgas 100.

We are at present carrying out further developments specific to the Australian (and US) market and fuels.  I will be bringing a suitcase full of mods to the meeting at Phillip Island for Marty and until then we are collecting data and I am giving Marty the benefit of my observations via e-mail and telephone.

The new spec will be more specifically for Avgas 100 or high octane race fuels and I expect another 5Hp or so. Question is do we need it!!

So to go back to the original question!! The best “peak Hp” CR250 I have ever had on my dyno produced 62Hp. The “quickest and most winning” motor had just over 58Hp. So you see it is about spread of power as much as the figure itself. The most extreme example I have see recently was a customer who’s engine made 67Hp on “another tuners” dyno and he wondered why he was struggling to make midfield. We ran it on my dyno and it struggled to make 55 with the worst spread of power I have ever seen.

We produce both crankcase induction and cylinder induction race motors. I have both types of new motor in stock and I have no axe to grind. We exclusively use the crankcase induction motor for our team. The reliability is far better, due to much better support of the piston and the larger big-end bearing. Generally speaking the crankcase motor has much better low-end and over-rev, but in peak power terms there is not a lot to choose.

Alternative gear ratios from us are £125 UK pounds each. Tailoring the ratios to the circuit has the biggest effect for the heaviest driver/kart packages running the narrowest power bands. If I say Marty is running a standard box, it kind of puts a reality of what can be achieved with a good driver, good motor and good chassis.

All CR250 gearboxes from the mid 80’s to 2007 have had the same standard ratios, but the crankcase induction box has a stronger (wider) 5th gear and 13 (as opposed to earlier 7) spline shafts..

I am happy to reply and help anyone and it is my policy to be open and helpful to any competitor.

Marty just texted me from Eastern Creek. Quali 1, quickest at 1:38.93.

Can't wait to get "ON THE ISLAND" and meet some of you guys

Best Regards

Ian

[Viper Racing UK]

Hi Guys

So Marty claimed pole and won all 4 races with fastest lap in each.

It has to be said that there was not much in the way of depth of competition for Marty in the National class, but his times were close to were they need to be, reliability was 100% and we are collecting data all the time. It would be good to see a resurgance in the 250 National class in Ozz.

Sam gave me a call last night and he was having water system problems with the Yamonda. This restricted his results but he took fastest lap in races 1, 3 & 4. Warren McIlveen also had a perfect meeting and took the Div 1 (FE) class victory with 4 race wins.

Well done to all competitors and particularly to Marty.

The next one on the Island is the biggy!!

Best Regards

Ian

[.:DLR96:.]

can't wait to here what you think of the island and your race report.
don't forget the camera Ian