Author Topic: RX-7 Racing - Hodgkinson Engineering  (Read 8099 times)

Offline raceralexuk

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RX-7 Racing - Hodgkinson Engineering
« on: April 02, 2008, 01:58:13 AM »
RX-7 Racing - Hodgkinson Engineering
 
###############################################
 
Some of you may have noticed me around the forum for the last couple of months asking odd questions here & there, and trying hard to work out where to find a cheap FD3S for a project. On Monday (30-03) the search ended - finally got the RX we\'d been looking for!
 
Plans for the series we\'re going to be running in are sketchy at the minute, but we\'re going to try to build the car to comply with following pretty similar classes:
 
BRSCC LMA Euro Saloon and Sports Car Championship (class A)
Nippon Challenge
EERC Britcar
EERC Production S1
 
Whichever class seems the most worthwhile competing in towards the time of completion, that\'s what we\'ll enter in to.
 
Ok, so as it looks now, here are a few pictures:
 




Removal of the interior has begun, ready for it to be sent off to have an FIA approved multi point rollcage fitted by Safety Devices.
 
A list of some of the planned work besides that to bring the car up to the correct regs, in no particular order, is as follows:
 
- Side exit exhaust
- Standalone ECU (Probably megasquirt)
- Peripheral port
- Convert to single turbo (aiming for a reliable 420-440bhp)
- Manufacture complete new wiring loom
- Ground effect venturi tunnels
- ATL 80 or 100L fuel cell
- Removal of all pulley driven systems from the engine
- Alternator placed on transmission
- Electric water pump
- No A/C, no air pump, etc
- Kaaz 1.5 way LSD
- Mazdaspeed PPF
 
etc, etc, etc..
 
By the way about "us" - Dad & I. My Dad\'s an engineer through & through, and well known as a racing motorcycle engine tuner. Myself, I\'m only 20, a motorsport engineering student & I work at Donington Park. I\'ll be the driver - naturally ;) I started racing karts over a decade ago, won 4 championships in different classes, ending up in 140mph Superkarts. Last year I raced in Formula Ford. Did pretty well but something was missing. Then at work I drove somebody\'s RX-7.
 
The rest is history...

Offline AtomicRex

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« Reply #1 on: April 02, 2008, 07:32:15 AM »
Hiya
 
Great to hear that another Rx will be out on the tracks....it can only do the Kudos of the car a great boost!!!
 
Send us an email
 
Would be good to chat to you, we maybe able to help
 
Cheers
 
Jon
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Offline Brett

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« Reply #2 on: April 02, 2008, 08:35:51 AM »
Good luck - would be great to see a build diary etc of how you get on :)
At the end of the day, it\'s meant to be fun - not a political movement! :burnout
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Offline BlitzBoy

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« Reply #3 on: April 02, 2008, 09:29:09 AM »
good luck with it , but dont go Peripheral port you simply just dont need it for 440bhp, plus a PPort will take time to do with loads of custom parts needed to be made, a simple street port will do with a decent turbo GT3540 or T04R for 440bhp
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Offline AtomicRex Racing

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« Reply #4 on: April 02, 2008, 06:47:20 PM »
You will struggle to get onto a lot of uk circuits with a peripheral port as they are loud.  Very cool, but loud.  
This video is of a 20b but you can see how it sounds, like an f1 car
click here

some of the things on your wish list we have spent a fair bit of time designing and getting made for our own cars, of which most isnt up in our vendors area, so if we might be able to help, please let us know.
« Last Edit: April 02, 2008, 06:50:45 PM by AtomicRex Racing »
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« Reply #5 on: April 02, 2008, 08:32:52 PM »
Quote from: AtomicRex Racing
 
This video is of a 20b but you can see how it sounds, like an f1 car
click here

QUOTE]

Wow, that does sound good ......... pure ear porn :Thumbs-up

Looking forward to my yearly dose of F1 ear bashing at the Grand Prix.

J.

Offline raceralexuk

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« Reply #6 on: April 02, 2008, 11:56:35 PM »
Thanks for the comments guys.
 
Despite the drawbacks of the peripheral port option (as you\'ve pointed out: noise, parts fabrication needed, wear, etc) we\'re still very keen to work with the idea. From our point of view getting the noise levels down to something sensible will be the main obstacle. We can fabricate anything that\'ll be needed to run peripheral port housings. We want to move away from using the factory intake plenum to something which would be considered more conventional in racing terms.
 
AtomicRex Racing, what kind of parts are you refering to? I could well be interested.

Jon, I\'ll drop you an email when can I find the time. Right now my days go work, car, a few mins on the internet, sleep, work, car, internet.... :2Rolleyes
 
Ok, so today\'s work was nothing that hasn\'t been done before. Still removing all the crap that we don\'t want from under the bonnet and inside the driving compartment ready for the roll cage. Wouldn\'t mind getting the doors all done while the shell\'s away being fitted up. I\'m going to use bolted in lexan windows with sliding openings. Does anybody know of a decent firm which can supply these to FIA spec?

Offline DRAGON

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« Reply #7 on: April 03, 2008, 12:29:39 AM »
Side exit exhaust
- Standalone ECU (Probably megasquirt)
- Peripheral port
- Convert to single turbo (aiming for a reliable 420-440bhp)
- Manufacture complete new wiring loom
- Ground effect venturi tunnels
- ATL 80 or 100L fuel cell
- Removal of all pulley driven systems from the engine
- Alternator placed on transmission
- Electric water pump
- No A/C, no air pump, etc
- Kaaz 1.5 way LSD
- Mazdaspeed PPF

I find the spec really bizarre, from the incredibly extreme of a PP and alt on trans, to the obvious things like removing air-con or MS PPF!
I will be fascinated to see this one develop.
Theres a guy on here called Mcarthy, hes quite experienced with this sort of project.

Offline raceralexuk

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« Reply #8 on: April 03, 2008, 01:26:48 AM »
As I said, that list was only some of the planned work. It\'s such a big job list I don\'t like to remind myself of it too often :rolleyes:
 
The power steering pump has been removed, along with the AC and the ABS:

 
Next up to be slung is the air pump & power assisted brake stuff. To add to the \'mod\' list, the following are also planned for some point:
 
Electronic PAS (Corsa C type with in-car adjustment)
 
Mazdaspeed PPF (need help finding one - anybody?)
 
Racing shocks (most likely Ohlins - more research needed)
 
A bloody big full width rear wing. That\'ll probably have to be made to order.
 
Single wiper blade
 
Porsche Carerra cup tyres (F:18/235 R:18/285, forget the AR, but ~30F, 45R)
 
Brembo GTR brakes (Fronts at least, possibly Brembos on the rears, or maybe the Mazda fronts remounted.)
 
Vented & drilled disks w/aluminium bells all round. 350mm diameter discs on the front.
 
Bruso digital steering wheel. (Karting wheel. Displays RPM, a temp, speed, lap times. Rewiring to enable it to use car\'s power supply instead of onboard battery, adding backlit LCD\'s, quick release boss) - should look the business in car.
 

 
Pedal box floor mounted with brake bias bar.
 
8" multi-plate racing Titon racing clutch.
 
All rubber suspension bushes have been remanufactured in a special nylatron (not going to give the secret compound away though!) Each suspension bush is three parts - \'top hat\' shaped main section, a ring on the other end to stop float, and a machined and lightened steel pin. I\'ll post some pictures of these up soon see what you all reckon.
 
Engine, diff & all powertrain parts will be solid mounted. Either on nylatron or aluminium. Yes, it\'ll shake the hell out of everything and probably crack the subframes, but we\'ll just have to deal with that if that\'s the case.
 
###############################################
 
As I said, I\'m really on the look out for a Mazdaspeed or similarly lightweight/strong PPF. Also looking out for FIA approved lexan side windows with sliding openings in.
« Last Edit: April 03, 2008, 01:28:50 AM by raceralexuk »

Offline AtomicRex

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« Reply #9 on: April 03, 2008, 08:05:38 AM »
Before you go much further you need to stop and talk to us!
 
It will take 1 minute for you to either give me your phone number or for you to phone me!
 
I admire your brave attitude....but you are, from what Ive read so far, about to make some major mistakes.....and we know....weve been there!
 
For your points so far....
 
Wiring, you cant run a car without a battery....we are developing a wiring system for the car at the moment, that will save a lot of weight
 
ECU and Dash this is something else we can supply, plus data logging should you wish to find out how quickly the chassis is about to split
 
I question why you want a side exit exhaust? Is this a show car?? We\'ve invest a 5 figure sum into getting the exhaust to work right......these cars are loud, get the wrong exhaust and its end of day at the first race. 108dB is easy to get over, we failed just because the centre box was removed. We also have our own manifolds designed for the job.
 
The aero side, unless you have a fortune or go and buy one of the off-the-shelf diffusers then you are adding weight and no effect, we have all the moulds for this very job
 
We know own the rights to an Rx7 cell made by ATL, it is 107L and comes complete with all of the dry breaks you need to run with in Britcar.
 
The water pump is a kit we have put together already as that is the same method we are using, all of the radiators and tanks are made
 
Why would you want to put the alternator on the tunnel....there is no where to fit it, the main leads go from Cut-out unit to the alternator and then to the starter motor....start moving these things and you will be adding a lot of weight.
 
we supply the Kaaz diffs
 
what is the PPF?
 
I see you\'ve already questioned the steering rack....why run with power steering? If you are used to Karts then you should want to move away from the lack of feel that is inherent with PAS, also when are you going to get the time to adjust the PAS in a race? This isn\'t F1 where they are tweaking the maps and adjusting bias mid lap, you are only adding items that can potentially go wrong, that is the other reason for going to a manual rack.....what can go wrong with it? You are still putting a load on the engine, instead of drawing straight from the engine using the PAS Pump, it is a load on the alternator. Going off the transmission will be inefficient as you will already have losses in the system so to make the same charge will require more work on the engine
 
Racing shocks...weve got Nitrons working with us to set the car up and get an ideal balance using 3 way adjustable shocks
 
Why do you want a "bloody big wing" if you are investing into ground effects? The whole idea of using the underneath method is to run a smaller wing, that creates less drag and is there for fine adjustments
 
What are you doing with the bodywork to get a 285 under the rear? Are you planning to run a crazy offset??? And why running so high at the rear? the difference is incredible, if you are trying to get the car to sit with the front slightly lower than the rear....then thats kewl, but do it via the suspension geometry not by whacking drag tyres on the rear
 
Fitting the front brakes to the rear means you wont have a mechanical handbrake. Also, ask Brunswick, it wasn\'t the best idea!
 
Going with the floor mounted box was something we looked at doing, but it felt all wrong....thankfully I was able to return the box and get a refund....not cheap! We now manufacture our own pedal box, that has its own master cylinders and bias bar for front and rear brakes.
 
Don\'t solid mount everything.....its good to have some compliance in the car. you are making the chassis very stiff by sticking a cage in....we are authorised dealers for custom cages now, and it will rattle your teeth out! There isn\'t that much power lost through the normal bushes, but I do wonder whether the extra shake rattle and roll will have an affect on the shocks
 
We thought about Titon, but ended up going with Exedy
 
We have the lexan you require, along with Carbon Fibre doors and tailgate
 
Sorry if this seems to be a lambasting, its not! Just think you need to step away from the tweeks catalogue and calm down a bit. Chat to us, it doesn\'t cost anything these days and it will, I\'m in no doubt, save you a fortune.
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Offline TonyC

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« Reply #10 on: April 03, 2008, 09:15:13 PM »
Glad to see more people putting the RX7 on the circuit for competition. Do speak to Jon, and myself I\'m sure we can help in alsorts of ways. Check the regs though for where you want to race though - and then build to those regs. From what I can recall of the regs you have listed they do seem to have some clashes in what you can and can\'t do.
Why not come to the Nippon challenge, new series with some TV coverage - a good oportunity to get in at the start of what will hopefully be a popular series in a few years.
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Offline raceralexuk

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« Reply #11 on: April 05, 2008, 02:45:45 AM »
Jon, I have your number. I\'ll try to find the time to call you tomorrow, but if not I won\'t disturb you on Sunday so instead we\'ll speak on Monday.
 
Anyway Jon, you must give us more benefit of your doubt! We shouldn\'t have to justify our various trains of thought to you :Giggle Everybody works differently, and nobody wins anything by simply copying the next bloke.
 
Nevertheless I\'ll be very interested to speak to you. Of course we have no experience of running an RX-7, not even on the road. So, I\'m sure that to hear of your previous misfortunes would be helpful to us! Some of the things you sell sound like they could potentially be good for us too.
 
Regarding the PPF - Power Plant Frame. I read somewhere that there is a Mazdaspeed one which is lighter and possibly a bit stronger? Sounded useful.
 
Side exhaust? To aerodynamically clean up the underbody.
 
Alternator on the tunnel, to lessen rotational enertia of the engine/to be different/why not?!
 
As some of the races we\'ll be entering will require long but still very quick stints, driver fatigue is a big enemy. I\'ve driven quick cars without PAS, and my arms often complain about it after not so long. I\'ve not seen a GT-2 or GT-3 car recently which didn\'t have a PAS system fitted.
 
Getting a 285 under the rear bodywork is no problem.. We\'ve already fitted them to the 10" wheels which were on the car. No problem laterally, however the arch will have to be rolled back as they\'ll surely rub & we\'re going to try to get as close as possible to the 40mm minimum ride height specified by the MSA.
 
We will not be running a crazy offset by any means, totally the opposite.
The tyres are going to be that size because.. that\'s what I can get. I might be wrong in stating the aspect ratio. They\'re written in three figure form, 530/620 or something like that.
 
How will your custom cage fully fitted cost me?

Offline RobMatthews

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« Reply #12 on: April 05, 2008, 08:59:38 AM »
link for jons cages, http://www.mazdarotaryclub.com/forums/showthread.php?t=44648

Can you explain to me how a side exit exhaust is going to clean up the aerodinamics of the underside?unless you are going out though behind the front wheel? if thats the case where are you going to fit the silencer\'s required to keep this monster quite?Not sure if you said you were running an in car fuel tank?maybe it would be better to run a full exhaust under the car with a center exit out through the back,plenty of room then for silencers, minimal bends, and you can then run a flat bottom with a proper rear difuser that will aid your aerodinamics and you can possibly then run with no/very small rear wing to aid the flow of air over the car?(that being quoted from jon-atomicrex to me a few months agolol) he is definatly worth listening to as he\'s raced these cars befor at castl combe so...
If you still wanna go with an electronic pas then you also have the option from the citron saxo or pegoet 106 to,very easy to fit and come with 3 wires to connect with its own wiring loom with relay in. rob
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Offline AtomicRex

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« Reply #13 on: April 05, 2008, 09:26:12 AM »
Cheers Rob :Thumbs-up
 
A chat would be great....and dont worry about calling on a Sunday....plenty of other people do!!
 
As Rob says how can running out at the side keep the underside cleaner?
 
I can understand at the rear....but we have just the answer for this!!
 
There really isnt that much weight at the front, not like a big GT car, and thats what a gym is for ;)  But I guess the electric PAS is an alternative, just doesnt give you the extra feel and turn in.
 
Still not sure on this Alternator idea, Im open to ideas....but I think you are trying to over engineer parts too soon in the project.
 
We are planning to run at 60mm ride height.  If you are planning on running any underfloor aero then the last thing you want is the chassis to touch....you loose every ounce of aero in a dramatic moment then....we ran 70mm last year, and through the fast corners the front splitter was grounding regularly....and not through incorrect damper/spring settings
 
Its good to see someone else pushing radical ideas...much like we are, and yes its not good to follow like a sheep....but then again if it isnt broken why fix it?
 
I take your point about the rear wheels....I thought about this, and I guess with rolled edges you can fit a 10-11J wheel in there.
 
Anyway give me a ring...we might be able to save you some money!
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Offline BlitzBoy

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« Reply #14 on: April 05, 2008, 09:56:40 AM »
I still cant believe you are going for a turbo PP port still just for 440bhp.
Your main aim in racing I thought is too have a nice and wide power band and quiet for the track rules, PP port acheives the reverse peaky with a lot more power and lots of noise like a F1 car.
Trust me you will save a lot of money,grief and time going with a normal big Street Port.
I think you need to listen to the guys above they have real world experiance and know what they are talking about.

Also the Mazdaspeed ppf if ever slightly so lighter we are talking half a kilo, but it is a lot stronger and stiffer so ideal for racing as the standard ppf will eventually crack, I had two of the things but one on my car now and one I sold last year, you can still find them on the jap auctions
"Piston Killa" 3rd Gen\'94 \'Oldone Racing Full Bridge Ported REW 13b engine with SCR seals\'. HKS T51 KAI turbo BBM mapped Motec ECU

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http://pistonkilla.blogspot.com/
old spec HB T51 470 @ wheels @ 1.2 BAR, 555 @ fly 10.46 @ 130 @ 1.25 Bar
new spec FB T51 482 @ wheels @ 1.15 BAR, 570 @ fly

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