My 200mph budget build

turbotoaster · 2 Apr 2010 at 22:03

Ordered one of these today, should be with me next week.

It bolts onto the throttle body, the reason i went for this is as you see, it steps up in size about an inch along, but luckily it also steps up inside by the same amount, now normally the narrow part is where you bolt your silicone pipe from the intercooler to.

But because of the power im going for i dont want any reduction in piping from the my turbo to my throttle body im going to be cutting the smaller piece off and putting the silicone pipe directly over the larger part as thats 80mm in diameter, just like my intercooler.

turbotoaster · 3 Apr 2010 at 00:55

nope, the metal pipe coming from the intercooler to the elbow will be the same length as the distance between the 2 parts so that the metal will be almost touching, this will mean the silicone will only have a very small area in which is will be subjected to the 2bar+ of pressure

like so:

turbotoaster · 3 Apr 2010 at 19:22

nope, have never really needed to film it, got one where im testing out a £7 mini-camcorder but im only driving at normal speed in traffic so its not exciting at all

turbotoaster · 5 Apr 2010 at 01:12

Ryan-3 said:
Is it the 3Rotor engine with the Twin Turbos, or the other one with the single

who are you talking about sorry.
the 3rotor with twin turbos was racing beats car in america that did 242mph are you on about a certain top speed one or something else

silversurfer said:

Just some random stuff I collected on drag calculations

Code:

F = 0.5 C ?A V2

Notation
(ft=feet, g=gram, hr=hour, kg=kilogram, lb=Pound (force), m=meter, N=Newton, s=second)
Our calculation allows you to use a variety of units with all of the conversions completed internally. The units below are consistent units for the drag force equation.
A = Reference area as (see figures above), m2.
C = Drag coefficient (see figures above), unitless.
F = Drag force, N.
V = Velocity, m/s.
? = Density of fluid (liquid or gas), kg/m3.

Drag coefficients for various objects (photographs taken by Ken Edwards).





    *  Object --- (CD)
    * A typical bicycle plus cyclist --- (0.9)
    * Rough sphere (Re = 1,000,000) --- (0.4)
    * smooth sphere (Re = 1,000,000) --- (0.1)
    * Turbulent flow parallel to a flat plate (Re = 1,000,000) --- (0.005)
    * Laminar flow parallel to a flat plate (Re = 1,000,000) --- (0.001)
    * Hummer H2 (2003) --- (0.57)
    * Ford Mustang Fastback (1979) --- (0.44)
    * Chevrolet Camaro (1995) --- (0.338)
    * Toyota Prius (2004 - 2009) --- (0.26)
    * Bullet at subsonic velocity --- (0.295)
    * Man in upright position --- (1.0 - 1.3)
    * Flow perpendicular to a long flat plate --- (1.98 - 2.0)
    * Skier --- (1.0 - 1.1)
    * Wires and cables --- (1.0 - 1.3)
    * Empire State Building --- (1.3 - 1.5)
    * Eiffel Tower --- (1.8 - 2.0)




Example Calculation

Problem: Calculate the drag force on a 3" diameter rough sphere moving through the air at 90 miles per hour, with an air temperature of 50oF and air pressure of 14.7 psi.

Solution: The density of air at the specified conditions can be calculated using the ideal gas law: ? = (MW)(P/RT) = (29)(14.7/([345.23(50 + 459.67)] = 0.0002423 slugs/ft3.

The velocity needs to be converted to ft/sec: V = (90 mi/hr)(5280 ft/mi)/(3600 sec/hr) = 132 ft/sec.

The frontal area of the sphere is: A = ?D2/4 = ?(3/12)2/4 = 0.04906 ft2.

The value of CD from the table above is 0.4

Finally, substitute values into the drag force equation: FD = CD(1/2)?V2A = (0.4)(1/2)(0.002423)(1322)(0.04906) = 0.414 lb


(.31) (0.5) (0.0002423 ) (86907.04) (19.2673)  =  62.887007658866248  lb


294.8
0.00036345
86907.04
1.79 m² = 19.2673 ft²
OR 19 ft² and 38.50 in²

http://carspector.com/car/mazda/040681

Whats the max power and speed of this car prior to modding ?

I have a big car book listing details of every uk car sold in 1989. It has the Rx-7 down as being 205bhp and max 145mph. A 'twin scroll' single turbo from hitachi apparently. Only cost 21k , bargain

Mx5 was 10k back then :eek:

Mazda RX-7 (86-96)
Going on parkers info and the 8x rule a rough calc of power needed would be 626bhp and obviously much more then that if you wanted more then a crawl leading upto the top speed

the max power is 255bhp and 158mph from factory it also has a drag co of 0.31 and a frontal area of 1.79metres if you want to use that.

though i have heard the UK ones were only 237bhp due to loads of different crap added onto them and they say 156mph with that speed

My car was 39k in the UK as it was made to compete with the lower spec 911, mad that now you can pick them up for less than 3k

ive calculated ill need roughly 635bhp to do it within 1.5miles and 518bhp if i had unlimited distance(or the distance that car manufacturers have)

Though im aiming for 700bhp so i can literally turn up, select high boost, choose my braking point and then do a run, hit 200mph, back off then make bacon sarnies for dinner

turbotoaster · 5 Apr 2010 at 15:59

the mirrors have been proven to give 2mph extra over a mile and taping up the front end gives 1mph so both of them will be done, also ill probably remove the rear spoiler as its proven to not produce any downforce at all and only drag.

ill just use 255 tyres on the back so not really wide, same as whats on it now, just a thicker tyre to up my gearing better go from 255/40/17 to 255/55/17

turbotoaster · 5 Apr 2010 at 20:02

im wondering if he is thinking about the aero of the actual tyres them themselves as technically they are 4 big blocks there get pushed through the air, making them thinner helps with aero, but the difference between say 205 and 255 doesnt make a big enough difference to compensate for the lack of traction, if this was on say the VW straight or bonnieville then i can see it causing some effect

turbotoaster · 7 Apr 2010 at 08:41

ok next part of my ebay part special build arrived today

The elbow that bolts onto my throttle body, as previously mentioned the reason im going for this is to maintain my pipework size so that there is no airflow restrictions which in theory will maximise the air entering the inlet manifold, i know the differences are minimal, but as a famous supermarket once said, every little helps!

Got it £79 delivered which was the cheapest around i could find it

looks like this is the company thats paying china for it

have to say, casting internally is pretty poor, so im gonna spend this afternoon with some sand paper and smooth it all out

heres what i mean about there being an internal step, this is the point at which im gonna cut it off, hence losing the narrow part

Checking its the same size as my intercooler...good to go!!

Not sure what to do next, either order my 2 fuel pumps or mod my intercooler so i can fit it with my rad, will have a think about when i next get paid

turbotoaster · 7 Apr 2010 at 18:55

well there will be a 5inch pipe coming off the turbo to just behind the front wheel, no baffles, no boxes, nothing, im expecting massive noise, well over 100db at idle

turbotoaster · 7 Apr 2010 at 21:28

no, any forced induction engine wants the least amount of backpressure you can get away with.

look at drag cars for example, just manifolds and thats it.

back pressure can help certain N/A cars, though a lot of n/a engines can be tuned to not need backpressure and benefit as a result

turbotoaster · 8 Apr 2010 at 00:26

hows yours coming along anyway, all sorted now?

turbotoaster · 9 Apr 2010 at 09:32

yes your right, when i said certain cars i meant stock or close to stock engines, if you increase the size of an exhaust to large and you dont have an engine specced to match that sort of flow you can loose power, pretty much what you said only you worded it better and i forgot to explain it further

turbotoaster · 9 Apr 2010 at 18:47

the real greddy ones are stupidly daft for cost, something close to £200 i think, since its only a piece of metal then you are just paying for the name.

Bit like my intercooler, its a trust GTR replica, i paid £72 new, they are about £1000 from trust and the replicas has been run on massive power engines before.

the only reason i bought one is it makes piping a lot easier instead of trying to cut and plastic weld my original elbow.

Will be dropping my intercooler off next week with the fab company to modify to fit in my engine bay, id imagine they will have it for a couple of weeks but i dont mind as ive got to MOT and Tax the car at the end of the month to pay for

turbotoaster · 12 Apr 2010 at 00:17

well tonight i have been busy on my ebay elbow.

firstly i cut the smaller diameter off, i could have done it after the lip and it would have been simpler but hindsight is a wonderful thing!

after cutting the end off i used a dremel to enlarge it back out to the correct size, not sure neat but not to bad, stops the restriction in my pipe work by making it 70mm internal diameter instead of 60mm

i then used my grinding bits to take out all the bumps, casting marks and general crappyness, it still looks rough in the pictures but feels silky smooth.

this took me 2hrs to do in total and its not a fun job sitting in the kitchen working on it, got pins and needles in my hand now!

turbotoaster · 22 Apr 2010 at 14:15

got myself a decat pipe for my birthday this year, even with the big turbo ill be running a 3inch exhaust on the road as due to running low boost there wont be massive back pressure issues and it keeps the noise down to semi-sensible levels........to say its loud compared to when it had a CAT on it is a bit of an understatement!!
When i started it up i crapped my pants, thought the decat had fell off, my neighbours werent to impressed!

Though its much better from 7-8krpm now as the ports where being heavily restricted by the CAT.

Big difference in weight

new gaskets and bolts which is nice

checked flanges and they are both true and flat

had to jack the decat up so i could get the lower brace back on, but all bolted up!!

video of starting it up

http://www.youtube.com/watch?v=0oiKRYFv2I8

turbotoaster · 22 Apr 2010 at 14:59

thats what they sound like with big ports, very rough sounding as its got massive overlap, on stop ports they are a lot quieter and smoother sound

stock car with decat is about 106db, mine is probably closer to 110db

turbotoaster · 23 Apr 2010 at 18:45

http://www.youtube.com/watch?v=pzRRHov_KUY

took a little bit of fueling out at idle and seems to calm it down slightly

turbotoaster · 20 May 2010 at 01:20

hey guys, not much of an update but id mention a couple of things anyway.

since im gonna need all the help with my brakes to stop from such a speed i stripped down both calipers and rebuilt them, was a bit of a nightmare

was dirt in the fluid that messed up 3 of the pistons.

Eventually got the piston out to find it had some scoring and a burr on it:

With similar scoring inside the caliper piston recess:

Was caused by pieces of grit in the system! This is despite there being dust seals and the main piston seal appearing to be in perfect condition!! Luckily the damage was not deep and came out very easily.

Rebuilt it with new pads and bled the brakes. This was the state of the fluid:

A bit skanky to say the least!

You can see its been a while since the pads have been changed!

the next update is that because of something happened today(which i will come onto later in the post) i decided to not go with my idea of having the intercooler in the engine bay.

I have decided to put it in the bumper area, now because of the large size of the cooler and the way the stock bumper wraps around the chassis area so tightly it meant that the bumper wouldnt have the physical density to contain the full cooler.

So i went on the hunt for another bumper, since it seems someone local has been using my front bumper to bounce there car off a few times a replacement was needed anyway.

Found this going cheap recently so picked it up including the lights that go in it.

Its a copy of a japanese bumper from FEED

As you can see it has much larger opening for air intakes, this will help to get more air travelling to the intercooler over a stock bumper aswell.

Suppose the final update was that today i got invited to santapod with redline magazine, was a lot of fun and interesting to see how the car did in its very basic setup(not much up on stock)

Arrive at pod at 10am, remove all the crap ive brought from home(food etc)

Have a wander around to see whats there and sign loads of paperwork to say im happy to die lol

Put the fuel back into my map to take it off economy mode, gotta love PIM voltage settings.

DRAG RACING

Leave it on stock boost for the moment, as im still on the basemap, thinking ill up the boost later on in the day when i get my 60fts perfect.

Since i didnt have a air compressor with me i just evened the tyre pressures out on the back to 20psi(since they are just old eagle f1s)and set the teins to soft.

So this is it, little bit nervous as not really sure what to expect and never launched a rwd car at pod before.

Drive around to the start line avoiding the water trap, move into position, rev up to about 5500rpm and go.

Pull of the line not to bad, once it hits 7krpm in 1st i get massive axle chatter and it shakes me stupid, change to second and pull to 7.5k, change to third, pull to about 7k and into fourth.........suddenly ive got no power, do the usual look in the mirror for white smoke(habit from owning a r5 turbo) look at the boost and ive got 0.01bar of pressure!!

Cross the line basically rolling

Feeling a bit disheartened thinking ok this sometimes happens to me but ill try again and hopefully the solenoids will be kind to me.

Pop into the timing booth to see what my 60ft was so i can see how much i need to improve(basically expecting a 14sec quarter and a 2.5 60ft)

Get given my slip to find ive done a [email protected] pulling a 2.1667 which i thought was pretty decent since i had no power for some of the run.

Thinking if the boost holds together for the run im hoping for a 12.5 at 110mph+

Launch on the next run and get a 2.1445 60ft so a little better but since im still getting axle chatter i know my launches need more work.

Soon as i go into third gear again no boost, try in fourth and same again, nothing, cruise over the line at 17.0822@57mph lol

Shame really as i didnt even get to try a 1bar of boost

my first run only peaked at 0.69bar

SPRINTING

Feeling a bit miffed about not being able to see what potential my car has i decided to pop up to the handling circuit.

Here is a rough picture from what i remember, there might be a better pic when its in the magazine, you launch at the startline on the right and the timing stops when you come to a standstill at the end.

The picture doesnt really show how extreme the salom at the end was, much more tighter and the cones were closer together

Pull up the start, asking the guy where do you go, advises me to drive around it slowly to find where im going then come back around and go for it.

Before i had a go i asked what sort of time to be aiming for, few guys say people are averaging around 33seconds, anything less than that and your fast.

So first go and ive now discovered ive got no boost....at all, since ive now only got about 150bhp i just keep my foot in as long as possible.

dont get out of the second gear the whole way around and use my handbrake to slow the car down as the big corner tightens up, then basically understeer my way around the rest of the course(foot welded to the floor as havent got the power to get back up to speed again)
Nail the brakes very hard at the end to help pull some time back.

Guy gives me a time of 32.5secs

Feeling pretty happy with it as i basically messed up the entire lap and didnt really know where im going.

Ask what the fastest time of the day was and its fensport corolla running 600bhp on semi slicks with a time of 28.4seconds.

i then started to put some more runs in and clean my lap up

2nd run 31.7secs
3rd run 30.0 secs
4th run 29.7 secs
5th run 29.6 secs
6th run 29.1 secs

which im not 100% sure where that will leave me in the end but i was in 3rd position when i left them to it at 330pm

Not bad for a car with no power, rubbish tyres(still 20psi in the back) and havent touched the suspension.

Found compared to other people i wasnt braking at all in the corners when they were, im guessing this was pulling my time back over the big power evos/scoobs etc

So overall a few positives to take away from it and a lot of negatives.

POSITIVES

running 12s at pod in a stock twins rx7 is so easy its unreal, 10psi on a basemap with no boost in 4th, old eagle f1s, i easily broke into the 12s so that should be a good thing to everyone out there who fancies a go.

Also shows my car has decent potential when running correctly and on decent tyres

Also i didnt break anything, was little worried about the diff as i have no brace and that i might blow the engine but all was good!

NEGATIVES

to be honest its kind of my fault, i really shouldnt have asked to go with the car not being in great condition, really showed up when i needed it the most.

Im sure with boost, set of 888 tyres and decently set up suspension i would have won the sprint competition so need to address these issues

got some pics off my mates phone, god the quality is poo!!

few from sprinting

turbotoaster · 20 May 2010 at 12:47

havent had a look yet, but im thinking its the solenoid that controls the second turbo, its just opening up and all my exhaust gas is going doing the wastegate instead of spooling the turbos up

turbotoaster · 20 May 2010 at 13:12

stav was in the 33s all day, was expecting him to be faster since he has 400bhp, 888s and weighs less than 1000kg.

i had about 150bhp, knackered road tyres and 1160kg and i was a lot quicker, think that shows the track was more about momentum than anything.

He also ran 118mph on the quarter which shows when he can get it off the line it pulls well at the top end, unfortunately his water injection nossle popped out so he destroyed his engine on the last run

turbotoaster · 21 May 2010 at 00:33

my new manifold arrived today, got it for a bargain price of £40 but bare in mind it needs a lot of work, ill get a friend to go over the welds again to make sure it doesnt crack, also gonna borrow my mates dremel to sort out all the overlaps on the insides, remember it looks bad now but for the money you cant expect much better lol

Once all the insides are cleaned up and its strengthened with a few well placed braces ill cut off the wastegate flange and weld on a 60mm v-band flange for my wastegate