Ask anyone who’s raced karts over the past two decades and the chances are they’ve driven a kart powered by Honda’s four-stroke GX160 engine. The much-loved GX160 is here to stay but is it time it was brought up to date? Could the larger capacity GX200 extreme engine with a more consistent power output and less than half the price of a top SP 160 engine be the future of four-stroke racing? We get the inside line from Pro-Kart tuners, RPM Motorsport.
Pro Kart sprint championship racing began in the early 90’s and at one time was the largest kart grid at many kart circuits, I can remember racing in the RatPro run Honda challenge at Wombwell with 120 karts and a separate final grid of just novices
Over the years chassis, tyres and rules have changed but the engines have remained the same base unit, out the box, remove the restrictor, change the valve springs and race, in theory. Due to the inconsistencies of the GX160 engine people tried to change the engine to get the most out of it they could, not all these changes were in the interest of the sport and a set of engine technical regs were produced to try to keep the engines to a set level and have been used for many years with specially designed test equipment to try to ensure that all engines are as equal as possible. Various combinations of the Honda GX, World Formula and Subaru engines have been tried over the years but it always returns to the GX160 but with engine units now costing well over £1000 is it time for a rethink before we lose all the Honda Prokart grids in the UK due to the high cost of competing at the top level.
Roger Pitchford Motors: RPM have come up with an idea that could turn Pro Karting on it’s head so we met with the RPM team at their workshop to find out the new concept.
KM – Ok Roger I have known you since 1994 when you could still fit in a kart seat and had hair, so before we get onto the new engines answer the question that most people ask, why do the 160SP engines cost so much?
RP – Because the MSA engine regs are an engine builders bible we have to produce an engine within those tolerances, out of a delivery of possibly 20 engines, when tested on the dyno machine you could get anything from 0 to 10 engines that are reasonably good but not up to top race standards as the engines are mass produced all the parts are slightly different in tolerances and its our job to strip all the engines to find the best bits and make the best engines we possibly can using only these parts, you can imagine the amount of wasted engine parts and engines that cannot be resold because nobody wants a basic engine.
KM – So whats the difference between a standard engine and an GX160SP?
PW – There could be anything up to 1.5HP at 6000 rpm between the 2 engines
KM – I can see the wastage involved in getting a top race engine but do you think that you have contributed to the demise of the Pro Kart grids as a lot of drivers cannot afford these engines and stop racing as they can no longer be competitive?
RP – No holds barred then! Ok yes if you put it like that then yes there’s no doubt that we have been part of the problem, as drivers demand more it invariably costs more it’s been a vicious circle.
KM – So why bring out a new variation of the engine if grids are falling?
PW – In sheds and garages all over the UK drivers have pro kart chassis ready for racing but they either don’t have the cash for new SP engines allowing them to compete on a level playing field or can only race a few times a year and cannot justify buying them. The new engine will allow them to race competitively at a fraction of the cost.
KM – I see it’s a GX200 engine does this mean you want to get rid of the GX160 engine altogether?
RP – God no! This is just an alternative and the drivers will be the judge of it, they will decide, we don’t for one minute want to stop the GX160 engines, they are the recognised MSA championship engine for Senior, Junior and Cadet championships and always will be, we hope that it will be an alternative grid for owner driver sprint and endurance meetings.
KM – So how much is the engine going to be?
RP – £400+vat?
KM – That’s a great price, for how long and when will it go up to over £1000, don’t forget this is to be published and we will keep you to it – forever!
RP – Hate you Capenhurst! We will fix the price for 3 years depending on the retail cost from Honda of the base unit and will only increase in line with that.
KM – OK that’s 3 years but then do we go up to the £1000 mark?
RP – I might regret this but after 3 years any engine increase will be in line with inflation. Happy now?
KM – Nice one that’s what we wanted, and in writing as well! So how can you keep the price down to £400+vat per engine?
PW – Each engine is rated 7.2/7.3 HP on our dyno machine (could vary slightly on other dyno’s) and to get there we can make any adjustment to the engine we want to which allows us to balance them and standardise them throughout the rev range, because we can do this to every engine we buy there are no wasted parts or motors making it all cost effective.
KM – That’s fine but how do you keep them all level and stop drivers making their own adjustments?
PW – All engines will have a seal on the crankcase, head and carb and nothing will be able to be changed, it is to be an economy engine and this is the best we to do it.
KM – How do you intend to control the engines if they are used at many different circuits?
RP – Obviously if a driver buys engines they can use them anywhere they want to but if they do a race meeting at any circuit for example, PFI or Stretton in an owner driver meeting or championship then there are certain rules associated with the engine. Each circuit will be supplied with spare engines (depending on grid size) the race organiser can change any engines for a new one at any time if he feel that there is a problem, at the end of the meeting the winner or any other driver can have his engines changed by the organiser or scrutineer, it’s up to the discretion of the circuits involved. There is also a buy back available at standard engine price and this can be arranged with each circuit. We also reserve the right to check any engine at any time to ensure it is within the stated engine limits, this could happen at any race meeting with our mobile dyno unit.
KM – Will there be any guidelines for circuits?
RP – Yes we are just working on a guideline sheet for any circuit that wants to run the engines within their club meetings
KM – What about service charges?
PW – these will be the same as the 160 engines as all service parts are the same but we are working on a possible service exchange system which will possibly work out cheaper.
KM – So who’s running the engines at the moment?
RP – we are running at PFI on their Sunday owner driver meeting and also we have a grid at EPEC in all the rounds for the pro teams and all the top teams are now running the engines. If we are at the sprint meetings like PFI drivers can hire engines from us for £50 per engine per day if you arrange it with us before the meeting, we have a lot of interest from circuits who have not had a pro kart grid for years and drivers who had given up sprint racing due to high engine costs are returning so it is working we are getting drivers back onto the grid.
KM – Does this mean that the GX160SP engines are going to be worthless after drivers have spent a lot of money on them?
RP – Not at all the 160’s will still be run within the MSA and at non MSA meetings alongside the GX200 extreme and if drivers want to change to the faster, cheaper engine then they can always sell them to the cadet drivers who always want top engines.
At a recent meeting at PFI Roger and team supplied the engines on a pool basis drawing the engines by number, most drivers had them fitted within 30-45 minutes and ran them throughout the day with no problems handing them back when finished. The lap times at PFI were 1.5/2 seconds a lap quicker, with more engine performance throughout the range. Speaking to all the drivers there were no negative comments from anyone, only encouragement and support.
So love him or hate him Roger has taken a big move forward in the pro kart class and a massive investment to try to revive the entry level class of karting, its true that we were losing drivers every year and something drastic had to be done, this could give the class the boost it desperately needs with a long term structure put into place with set costs, contact RPM for more information.
T. 01543 473548 / www.rpmpower.co.uk