Max BHP from stock twins?

[Oedipus Rex]

I\'m going for the 1600 secondaries because I want to crank a bar of boost out of it. I know its pricey but compare it to putting a single in. And even if you do put a single in you\'re going to have to put some 1600 in anyhow

[JP825]

Where are u getting it from? Any recommended place (cheapest)?

I will probably have to get a set too. :p

[monkey-fd3s]

Hi,

It can be confusing when you first get going, hopefully some of this will help.

1) Chargecoolers work using water or ice to cool the air charge i.e. they are a air to water cooler and usually have a separate rad to cool the water.  For short blasts they offer more cooling and they don\'t require airflow to cool the intake air.  Essentially they are good for applications prone to heat soak or for short drag style runs.  

2) There are a variety of intercoolers (air to air coolers) available for the RX-7.  These range from:

SMIC - stock mount intercooler - these mount in the stock position and are usually larger than std.  They fit nicely with stock components but don\'t generally offer massive gains.

FMIC - very very very good at cooling air but a trade off it the fact that it sits in front of the rad and hence you get heat soak at low speeds and may see increased rad temps as a result.

V-Mount - the rad and IC fit in a V so that both get good airflow.  The IC doesn\'t get as much as in a FMIC position but should see a car that has to do daily or stop start hauls through slightly better.  

It\'s everyones opionion at the end of the day so other people may have a different view.

Don\'t be too confused you should be able to achieve the 300RWHP you are looking for on the twins, just make sure you do it sensibly.

As for scoobies, I used to have on before the RX and I have to say corner for corner the average driver is going to be faster in scooby as they handle very very well with min effort from the driver.  However, the RX in the right hands will kill any WRX... i\'ve yet to race one... (not that i\'m the right hands by any stretch)

As for essex - i get enough shatso\'s and corsa\'s trying to race me in London but I want to race something interesting... I\'ve seen and driven enough modified "chav" cars to know they aren\'t usually worth the time to race.  Plus they usually try and race you in an area where you are likely to cause an accident which is just stupid.  I welcome them to bring it to the track any time.

So my next point is that I am slightly confused....

"I\'m going for 1600 secondaries as I want to crank a bar of boost out of it".

I run .98 KG/CM2 on my car with my current setup and have more of a problem with overfueling than underfueling (.98 is just under 1 bar)

Strange but I guess every car is different.

Dave

[Oedipus Rex]

I think you hit the nail on the head with the every car is different point. There are so many factors determining how much fuel you have. Because of my mods, my bar of boost should be getting me around 350 at the hubs, so shes generating a fair amount of power there and very thirsty for the fuel.

[TonyBlair]

Excellent write up about intercoolers, charge coolers etc. Nice one mate  

I know what you mean about chavmobils... They know they\'ll get beaten in every scenario so they take stupid risks to try and get in front on you. I often just let them go... I\'m not interested in racing around the town centre AT ALL!! It\'s just ridiculous, so many potential accidents - too many cars pulling out of side roads, or small children running out between cars.

All the best,
Jon

[Initial-D]

The new Scoob and Evos are very quick at accelarating and in the corners too! They tend to loose out in the top speed department to standard FDs.

But when you look at how much they cost and how new they are compared to an FD, we can\'t complain!:D

[monkey-fd3s]

Yup i agree with you there.

Scoobies are just too common for me - they are really nice but the new ones tend to be driven by people (at\'s not all of them but most) who have no clue about what there car is or how it works...

Now personally i\'d like a go at an R34 or 911 Turbo.

[Warthog]

WARTHOG.

1994 RX-7 FD3S.

Street Ported HURLEY engine with 3mm Racing Tips, running Stock Twins, HKS Exhaust with FEED de-cat mid-box, HKS Induction kit, APEXI ecu + commander, Bosch 044 Fuel Pump, 1300cc Secondary Injectors, GREDDY Pulley Kit, PWR  Radiator, PWR Charge Cooler Kit, Plugs 2x10’s and 2x11’s, Magnecor 10mm ignition leads, GREDDY Boost controller, Blitz Turbo Timer, XTREME Single Plate Clutch DSB_XHD, Lightened Flywheel and counter balance, RE:WORX Diff Brace, RE:WORX Gearbox Brace, RE:WORX Swirl-Pot, RE:WORX Water Injection Kit, FEED Engine Brace, B&M Short Shift Gear Stick, TEIN Adjustable Suspension, Front 235/40/ZR18, Rear 265/35/ZR18 Dunlop Super Sport Race Tyres.

[TonyBlair]

That\'s quite a shopping list mate.  What\'s a swirl-pot by the way? Sounds a bit magical.  

[Wav]

Originally posted by TonyBlair
That\'s quite a shopping list mate.  What\'s a swirl-pot by the way? Sounds a bit magical.  

It\'s how you predict the future and tell peoples fortunes after you\'ve drunk your pot of tea and "swirled" the leaves around a little bit! :rollin

Very magical indeed,

Paul:p

[Warthog]

It ensures that you don\'t get air being sucked through into the fuel pump. You do need it when you upgrade your fuel pump. It stops detination due to air in the fuel. Some people have got away without it by ensuring they always have 1/3 tank of fuel. But whats the point in trusting to luck when you can prevent it. Also ensures your fuel pressure from the tank, very much a must if you are going to be doing any real track time. HTH.:wave

I\'m off to work now. I will try and post my views and first hand knowledge of Charge Coolers later, for your info.:wave

[John Yorke]

Most of the Charge cooler writeup is correct i would add though they do work very well over a long period of \'sustaind boooost\' prior to fitting WI [- which is a must if you are looking for VERY big power out of twins =320atw] I would see intake temps of C30 -35- that was running 1bar on twins with 317atw

The charge cooler is a very inexpensive alternative to the FMIC, the install is a lot less expensive, the cost of buying is less, it does not rely on cold air to cool it [hard to find in summer!] The other problem with FMIC is if they are not installed with the consideration of allowing sufficient cooling throgh to the water rad you will experience overheating [engine wise] which is very bad [consider the rotary as a very hot running engine as standard - if you put more boooost through you generate more heat which has to be dispelled - stick a great big FMIC in front of the water rad - you have the added problem of high water temps.], you need when modifiying to consider all angles not just getting more power from the engine but is this [or that] mod going to have a knock on affect?

Once you have this all powerfull engine you then find stopping the beast is a problem - traction is next - getting it around a corner faster.................................... they go on and on:confused:

[ro284]

I know nothing about this! but does it follow that a charge cooler will cause less Lag than a FMIC? and have quicker throttle response?
Just as a matter of interest, Bob

[Warthog]

RO284 in answer to your question YES. The c/c is so much closer to the turbos and plunum the air flow is more direct.  The 2nd turbo comes in  that quick it\'s a matter of what turbo lag.
John York has covered most things, the only thing i will add is that if you are going to go for big bhp on twins then i am just going to experiment with removing the air-con rad and drop in my old engine rad with a couple of fans on it to use as my cooling rad within the system. The reason for this is that putting so much boost through the twins heats them up a lot and my intake temps are suffering a bit 45c under continued high boost runs.
I do have a number of options open to me 1. as above . 2. i have not as yet sorted out cold ram air to my aopexi\'s but i will before RS11. 3. I am working on a idea to scoop cold air from under the car to blow over the twins to assist with cooling them.
John is spot on when he says you just can\'t go for big bhp and think everthing else will be fine, you have to balance everthing. To each force there is an equal and opposite force. Make more power=make more heat=make more cooling to reduce that heat.
As we have now maxed these twins out i can now work out how to gain more power by doing more cooling. I will eventually get to the point where i am happy and have reached the targets that i have set for myself and the car. At that point depending on how well i can control turbo heat i may well put a set of the biggest twins i can fit in the engine bay or just go very big single. I havn\'t got to where i want to be yet, so i will cross that bridge when i come to it.
Anyway enough of me whittering any Q & A\'s you have feel free to ask and if you want pics etc then they can be supplied. I will be at RS11 so feel free to say hello and you can have a good look at the engine etc and take what ever pics you may wish yourself.
Good Luck in your search for what makes the car feel right to you.:wave :wave :wave :wave :wave

[monkey-fd3s]

I wouldn\'t 100% agree with the chargecooler write up above.  They are very good but both the cc and IC options have pro\'s and cons nothing is a free situation.

With a CC if you are cooling the water using the engine water and rad you aren\'t going to get a great deal of performance, this is the first big no-no when using a CC.  The CC system should be separate, that means a separate RAD, water pump, header/ice tank and cooler core.  By the time you have all that made and fitted it\'s going to cost in the region of a FMIC setup if not more.  BUT it will offer very good performance as it can cool effectively in more extreme conditions and works well over a variety of environemental variables.

We ran a CC on our dragster with some good sucess and it performed much better than an IC arrangement on the strip.  I would imagine on the street the performance would also be generally better assuming you use a separate setup.  However you\'d be fitting in another rad/header tank and lots pipe work, making the engine bay untidy and quite tight.

The IC on the other hand simplifies the fitting, but won\'t offer the best performance.  Once you have good airflow you\'ll see good cooling performance but unlike the charge cooler it\'ll force intake temps up when you are sitting in traffic and in general day to day operation it won\'t work as efficiently.  But that\'s the trade off between the ease of fitment/cost/compexity of the two systems.

On my V-Mount I see average night time intake temps of around 21-23 degrees C.  On a sunny London traffic day it\'ll hit 40 in traffic and drop to 30 in a light cruise.  On a cold night it\'s been down around 10 degrees.

Hopefully it\'ll get cooler once the ally work is done in the engine bay.

I\'m not saying anyone is wrong here but I\'m trying to give a balanced perspective - both solutions are good and it again depends on the car and purpose as to which is the best route for you.