My 200mph budget build

[turbotoaster]

since this is my thread, i thought id do a little rotary porting 101 if people are still reading.

to understand a rotary engine you have the imagine, how could i make my engine simpler, what things limit me when im making power(naturally asp)

Well first we look at cams, stock cams are normally pretty mild, with low lift and short duration, so, they dont allow the valves to open much or for long......doesnt allow much space to get that air in there does it.

So we change over to a more aggressive cam which does it....more power!

then we move onto the head, because yes the valves are nice and open but the air still needs to get down to them by passing down a small hole, increase the size of that hole(port) means we can more of that valuable air to the valves.

now from reading that you understand the basic principles of piston engine tuning.

Now a rotary isnt some magical engine run on leprechauns and peanut butter, it must follow the same rulls as a piston engine.

But how it does this well....it swaps all that for just a hole, thats right, the cams, valves, valve springs, head.

Now i wont go into detail on how a rotary works, ill just explain how to tune them.

Before reading anything else below i suggest you watch this as i found this explains how a rotary works very well so everybody should understand it
http://www.youtube.com/watch?v=oGrD7FTFLJc&feature=related


Ok now you have watched it ill continue on.

As you saw in the video, the rotor has 3 sides, to make it easier, ill call the first side, SIDE 1.
the port where the fuel/air comes in is opened by one end of the SIDE 1, the air/fuel comes in, then is closed off by the other end of SIDE 1.

So you have an opening and a closing, just like you do with a cam to open and close valves.

Now this below is a typical stock port, the one you find on standard rx7s

when the rotor moves to reveal the port(open) the first part that is opened is the long left hand side edge, the mixture comes into the chamber and then the other end of the rotor closes the port at the top horizontal edge as it rotates.

So by making the hole larger in different areas you can affect when the port will be open and also when it will be closed.

these are 2 pics of my templates over stock ports so you can see what i have done to my engine

this is my secondary port(ie big one to help with high rpm)

as you can see i am making it open earlier a little bit, if you go to far you get overlap so loose to much low down power, but then you can see i have increased it a lot at the top of the port(closing) this is to help get the air into the engine, ie wait as long as possible before the port closes, this like duration on cams.

One last thing you should notice is the stock port has a flat top and mine is a curve, this is to help the engine make the power a little bit lower down and give me a wider torque curve, if it was straight it would close instantly instead of a lower close and a faster close means you make maximum power higher in the rpm.

Since the engine needs to be useful for many different things i found it would be best to not make a 10krpm screamer.

now this is my primary port, this is the one that the fuel goes down when in driving like miss daisy and generally pootling around.

Now because of i want the car to run around nicely on the street i want to keep this mild.

Now as you can see the out edge is ported much larger than the secondary port above, the reason for is the port is smaller than the other so i have more room to increase it without getting overlap.

if you compare the pictures apart from the length, they are the same width, showing that both ports now open and close at the same time.


Now thats the port timing done(like fitting cams) now because as you can see i have had to increase the size of the ports to get the timing right i have also allowed much more air to pass through because of there physical size....this is like porting out a head for it to flow more.

Pretty simple really, buy a dremel and a porting kit from b&q and do it yourself, does the same thing as porting a head and buying a set of expensive cams, valves, valve springs

 

[Matt82]

good thread and i cant wait to see this get going.

ill cross my fingers for you and the budget, becuase that like a tall order on such a basic income

oh, and £30 on food a month!!

 

[turbotoaster]

Not knowing a huge amount about cars I might be way off, but will you be looking to tune it to run on Av-Gas or Bio Fuel for the few extra horses it can give?

not on av-gas no.

Its a real pity that we just cant get E85 fuel like the americans can, yes i know a few morrisons do it, but not enough of them to make it worth while, if that was the case id easily make 700bhp on that and that would be the fuel and power i would run on the road after the event.

Ill just be down to pump fuel and water injection

are you fitting some kind of flat undertray for underneath the car mate?

Its not required to be honest, since im only going in a straight line on tarmac i dont really need a massive amount of downforce, the car being extremely low on the day will give any additional downforce.

If i had to corner at high speed or was on a loose surface(salt) then id look at that

 

[pzr vr6]

not on av-gas no.

Its a real pity that we just cant get E85 fuel like the americans can, yes i know a few morrisons do it, but not enough of them to make it worth while, if that was the case id easily make 700bhp on that and that would be the fuel and power i would run on the road after the event.

Ill just be down to pump fuel and water injection



Its not required to be honest, since im only going in a straight line on tarmac i dont really need a massive amount of downforce, the car being extremely low on the day will give any additional downforce.

If i had to corner at high speed or was on a loose surface(salt) then id look at that

i mentioned it to reduce drag not for downforce/ground effect

 

[turbotoaster]

ah i get ya sorry, ermm i dont think it will be required, yes it would help but not worth the effort, if i was maxing the car out at bonnieville or at nardi high speed ring then id say yes id fit one

 

[Lashout_UK]

It'll clean up the underbody airflow considerably and reduce drag, like PZR says - not difficult to make and well worth the time, if you can get the car in the air - a few flat sheets of alloy riveted in the appropriate place makes all the difference. You still need downforce, even if doing high speed runs (in fact, I'd go as far to say it's critical) - because as you accelerate up to speed the car can start generating lift instead of downforce, so traction and grip become lesser and you can find the car starts to wander about or spin up - leading to you having to back up, or just plain ol' losing control.

Being a fairly quick car in the first place there's probably enough downforce generated by the body - and as you say, because you've lowered the car you will improve downforce as you reduce high-pressure air buildup at the front of the car (which also helps with stability) and alter the way the air flows around the car.

You can improve downforce whilst still reducing drag by adding a little rake - so the front rides lower than the rear - could be cheap and easy......

For example, the Racing Beat Bonneville car has a big rear spoiler moulded into the body, to make sure the tail stays down, as well as a large diffuser to also increase downforce, as well as reducing drag - and it has quite a pronounced rake to it

Obviously a balance is required - you want maximum downforce with minimal drag - but you need enough to keep the car where it should be

Does the car have a front splitter or chin spoiler? There can be gains made by adding, or modifying the existing one

I found an extra 5mph on the top end on one of my old cars by removing the front chin spoiler - but that was a rather less elegant beasty

 

[Fevvahz]

Just to confirm - are you fitting a roll cage to the car?

 

[Lashout_UK]

I forgot too, if you add an underbody or even under-engine tray then that will help a lot with cooling, which can be a problem at speed

It effectively lowers the air pressure in the engine bay so fresh air will be more easily drawn through the cooling pack.

 

[turbotoaster]

the car does have a chin spoiler, from tests at mazda it does not increase drag at the front end so it will be staying as it changes lift coefficient from 0.16 to 0.10 to help keep it down.

also wind tunnel testing shows dramatic increase of air forced into the radiator ducts, the oil cooler ducts(which in turn flow to the brake cooling ducts) by having the chin spoiler compared to none(US base model)

the rear has a very low lift co of 0.08 anyway as the underside at the rear does make use of the air from factory to help.

Ive already spoken to racing beat about this, if you go back a few pages you can see an email from them about it.

I emailed them back and explained that this was on tarmac, the reason they ran a 5in ducktail spoiler on the back is to help grip on salt then you accelarate, there previous car spun the back wheels at over 200mph as there wasnt enough grip, your not gonna have that issue on tarmac.

the car comes with a under engine tray which travels pretty far back, it defo helps with temps from what tests have been done on rx7s.

and no the car wont be fitted with a rollcage, you may not like that, but im 6ft3, not really much room in there as it is

 

[Lashout_UK]

Ah good stuff then!

 

[Izi]

When he posted his project details on a public internet forum.

you always get that emotionally involved eh? bless your cottons.

sorry couldnt resist.

good luck with the build! i'll be following.

 

[ajgoodfellow]

Been following this with loads of interest - it's an awesome project!

 

[wez130]

I'm trying my hardest to resist, but i can't, Fox - i never aimed my comments at you - or anyone inparticular, but you were the only one to jump down my throat about it. Yes, it's an internet forum, OP is free to talk about his finances if he wishes to do so, but others (and like i said - not necessarily you) stick their oar in as to how can he be affording that with a part time job, who cares how he can afford it? THa's not what the topic is about, it's what looks like a very interesting project. Maybe 'green eyed' was the wrong word, but what is the correct word? 'doubters'?/. i dunno lol.

Last i'm saying on the subject anyway

 

[Fett]

But to hell with it, if your going to blow all your money on something, what better way to do it on building a car that can do a 200mph standing mile.

If it were a standing mile, I doubt I'd post in this thread as I would not have thought that it could be done...maybe that could be the next goal

Really excellent project with the 10k budget, please don't forget to update it. Good luck with the mapping and the cooling, both are going to be absolutely crucial. Having your foot buried for 30 seconds on a top speed run is going to bring any tolerance and clearance issues up sharpish

Not sure how many runs you'll be looking at on the day but take care and roll off smooth and triple check your pins/latch. Good luck, hope you do it.

 

[Jonny69]

I've got to laugh at a lot of the replies in this thread

YOU'LL NEVAR BE ABALL TO DO IT OH NOE!!!111

Fact is, people have been running 200+mph on the salt in 1920's, 1930's and 1940's kit for years, loaded up with lead weights to hold them on the white stuff and a pile of power up front to make sure it gets up there. There are even guys who drive the car to the salt, switch the axle ratio and run 200 and drive home again. I reckon you can do it and good luck

 

[Fett]

I've got to laugh at a lot of the replies in this thread

YOU'LL NEVAR BE ABALL TO DO IT OH NOE!!!111

Fact is, people have been running 200+mph on the salt in 1920's, 1930's and 1940's kit for years, loaded up with lead weights to hold them on the white stuff and a pile of power up front to make sure it gets up there. There are even guys who drive the car to the salt, switch the axle ratio and run 200 and drive home again. I reckon you can do it and good luck

Which sort of insinuates it should be a walk in the park. This is at Brunters, within 1 and half miles, for under 10K. If it all comes together, I reckon he might pip it and hope he does, but it is pretty difficult.

 

[[TW]Fox]

Last i'm saying on the subject anyway

I won't reply properly because I feel the thread is back on track now

 

[TripleT]

This sounds like an awesome project - will be watching with interest. Good luck.

I may have missed it but have you got a date set in your head for the attempt?

 

[Overlag]

nice project. £200 a month on a car really isnt that much.....

 

[turbotoaster]

If it were a standing mile, I doubt I'd post in this thread as I would not have thought that it could be done...maybe that could be the next goal

Really excellent project with the 10k budget, please don't forget to update it. Good luck with the mapping and the cooling, both are going to be absolutely crucial. Having your foot buried for 30 seconds on a top speed run is going to bring any tolerance and clearance issues up sharpish

Not sure how many runs you'll be looking at on the day but take care and roll off smooth and triple check your pins/latch. Good luck, hope you do it.

cheers mate, to do it in a standing mile id need around 800-850bhp in my car, have to run some massive tyres on the back to get sort of traction as that defo is a big drag race, prob something like 335 width hoosier/mt et streets would do it, thats 8cm wider that whats on there now, i think i can run 295max on the back with stock arches so bigger ones would be required.

i could get that power if i either added n2o or went to a gt45 turbo, though i would need to take the engine apart again for bridgeporting and clearancing

either that or a lot more power, rod tarry saff just hits 200 in a standing mile and he has narrow tyres, its just with nos he has over 900hp

Been following this with loads of interest - it's an awesome project!

thanks very much

I've got to laugh at a lot of the replies in this thread

YOU'LL NEVAR BE ABALL TO DO IT OH NOE!!!111

Fact is, people have been running 200+mph on the salt in 1920's, 1930's and 1940's kit for years, loaded up with lead weights to hold them on the white stuff and a pile of power up front to make sure it gets up there. There are even guys who drive the car to the salt, switch the axle ratio and run 200 and drive home again. I reckon you can do it and good luck

id love to go to bonnieville, just to watch them run, i wouldnt fancy running though, wheelspin at 200mph would make my bum chew a hole in the seat!

This sounds like an awesome project - will be watching with interest. Good luck.

I may have missed it but have you got a date set in your head for the attempt?

well im not 100% sure yet, im thinking it will be october time as that gives me time to get the money together and finalise everything, plus the weather should be cooler which will help with temps