Having a bit of time to kill recently and some friends who are quite handy at fabrication we hatched a plan to improve the intake side of the Enginetuner 99 Impreza.

I had 2 spare 99 manifolds laying about and handed them to my good friend Matt a local engineer, who immediately set about making a jig to hold the manifold at the right width.
The middle section was then removed and thrown away from both manifolds and the longer straighter sections of both manifolds were re-fitted to the jig.

Now we had a decision to make. Build a custom box inlet similar to the Forsa version for Newage cars.

https://www.google.co.uk/search?q=fo...24%3B800%3B600

Or something a bit different.

Matt being a resourceful kind of guy happened on his travels one day to find an old dive cylinder which he decided could be the perfect start.
Having cut it open and to the approximate length we had in mind.



He then proceeded to machine it out as it was over 15mm thick, ok for it's original use but a bit thick for what we needed.

It was then offered up to the runners and marked for cutting.






He'd also started to make the front end ready for the throttle body to be fitted to.



It was then handed to another good friend of mine Julian for some of the welding.



More on this later !

 

Part 2

Back from the first part of welding any unwanted lugs were removed and reqd ones re-made and welded back on in the right places. Vac take offs were drilled and tapped and a boss for 2 extra injectors we'd made earlier in the year was welded on along with the machined throttle body plate.









Matt then whipped it over for trial fitting before we decided on a finish for it.



I had thought about going carbon for a finish but we decided it can look tacky and went instead for something basic.



Fuel rails all fitted and time to pop it back on the car.

More again later !

 

Love it!

Subtle paint job too!

 

All fitted and wired up (Except the extra injectors as we're not quite ready for that yet
Coolant system bled, levels all checked and we're ready for the dyno.



Straight Tesco 99 was the fuel of choice to compare earlier figures from the car and to try and crack 600bhp on pump fuel.

Back again soon !

 

Part 3 (Mapping)

So car on dyno, all warmed up and part throttle stuff done and the car is already showing signs of improvement in it's VE as it's taking a fair bit more fuel especially higher up the rev range.
A quick run at actuator pressure confirms this, Red lines prior to manifold, Blue lines after manifold.



Pleased with initial progress, onwards and upwards gently increasing boost and tickling the timing and fueling as we go.



We cracked it ! 600+ on pump fuel and have lost nothing compared to the previous set up, it spools as well as it did previously and makes only 3hp less than it used to on race fuel at less boost too.
Now to try the larger Blouch turbo I have sat here waiting for testing and then on to race fuel mapping and setting the nitrous back up.

700+ ?

I hope so

 

That's a very nice graph/curve martyn
Not bad for a gas bottle !

Tim

 

Cracking results!

 

Very ingenious,the finish article and the results are superb.SJ.

 

So specialist tuners spend hours designing the internals of inlets with tapering lengths and internal trumpets and all they needed to do was use a tube.

Be interested to see a back to back against something like the cosworth manifold.

What's the science behind the improvement? There's a restriction with the size of the manifold after the throttle body in relation to it's inability to feed all runners efficiently?

 

As I said in the first line of my post we had time to kill and the skills to give it a bash, lol.
I'd had a look at what else was available and nothing retained sidefeed injectors which would mean a complete fuel system redesign too. I have Deatschwerks 1100cc sidefeeds which weren't cheap and work very well so I didn't fancy swapping to topfeeds.
We had no idea whether it was going to work and sang the Doctor Pepper song many times.
Thankfully it seems to have worked a treat.

 

As a basic rule of thumb by the way if you change inlet, exhaust, turbo etc and see more power for less boost you're on to a winner !

 

the million dollar question is would you make another one and how much would it be? I think it would go nicely with my new turbo...

 

Just reading my post back, sounds a bit sarcastic. Wasn't meant to read that way, I like reading stuff like this so appreciate you sticking it up.

 

No problem. We're now just over half way through fitting the larger turbo so more updates to come next week !

 

Larger turbo fitted and ran on Tesco 99 again and on the larger exhaust housing it was a bit of a flop. Swapped the exhaust housing over to a .82 and it made exactly the same as the GTX turbo 609.9bhp.
I've since swapped the fuel over to C85 racing ethanol and tweaked the map to suit and this was the result.


Flywheel power and torque



WHP and boost



And some pics of the car wearing her new boots.

 

Sorry but I can't help looking at that and thinking what a bag of **** it looks like especially with that front bumper.

I want it de-stickered with road tyres please . I can only imagine the looks people in exotica have on their faces as it murders them.

 

I am still a bit puzzled about this.

what is the real science behind the improvements? Why is there so much improvement over the old manifold?

is it just because you fitted the sidefeed injectors, not really the manifold itself?

 

 

Looking good Martyn !!

When are you next out ,you coming up to shaky sometime.

Not been out myself this year,have been waiting for modena gearbox parts from Australia for the last few months .

I'm swapping to hoosiers as well .

Hope to run end september or mid October

 

Yes m8, hoping to get back to Shakey soon but I'm gonna do some local testing first. There's a straightliners event this weekend at Dakota Raceway nr Honiton so I'll give it a shakedown there. Hopefully the weather holds out and I get to beat my current 10.63 pb.
I've softened up the rear end with some UK sport shocks and springs to get her to squat and the Hoosiers should grip a bit better than the 888s.
Taller rolling radius too 😊

 

Forgot my bumper sticker and to add the dyno video.

 

Well the weather threw a curve ball at the weekend making me doubt whether the drag radials were the right tyres for the occasion so back on with the R888s.
Got there nice and early and after sign on and scrutineering started with a few low boost runs. Car felt great on the C85 running very clean and straight down into the very low 11s at just 1.4 bar.
Time to raise the stakes.
High boost map selected and pull up to the line, she knocks out a 1.71 60ft going on to a 10.62 1/4 with a 137mph terminal, a new PB but still far shy of where it needs to be.
Now looking at dates for RWYB events at Shakespeare County for a proper shake down.

 

Very impressive motor Martin.Whats your mpg like then when your taking it easy

 

Bloody awful on C85 as you need 35% more of it but actually quite good on pump fuel. Seen 30mpg on a run ☺

 

That's impressive Martin considering the amount of power your making.I noticed you have a catch tank on your bulk head.How have you fed your breather pipes to the tank from the engine.Im gathering these was the same pipes that went to the air intake pipe to the turbo?Do you have a build thread on your motor that I could look at

 

All of the breathers from the rocker covers and the block are connected to the catch tank which has a breathable cap.

 

Stop prancing around with these 10s and get those injectors running and release the gas

I like bumper and tyres. In fact those tyres have done 9.51

 

Lol, we're on it m8, ecu side of things is under way

 

I'm interested in this too. Is the OE part so restrictive a Heath Robinson (no offence intended I hasten to add) affair gains so much?

 

None taken, lol.
It's hard to say without flow bench data I suppose but it certainly appeared to work in my case.
Don't forget of course that the stock manifold was designed with a completely different brief, they weren't concerned with revving to nearly 9000rpm or producing nearly 700bhp.