My current engine only has 4 injectors, and I think the ones I've got will not flow enough for the new engine. I need to know of some 4 cylinder engines that do 250-300bhp as standard so I can go searching the wilds of ebay for some new ones.

Regards,
Dave

there was talk of saab injectors for 300hp on here, I am sure the gentleman with the mighty twin charged kitten would know the answer,..

IIRC there are some Subaru lumps that have that kind of power output, albeit with a large turbo, but they should be able to provide you with the necessary injectors.

Also, the Mitsubishi Lancer EVO is another 4 cyl that comes from the factory with those kind of levels.

Definitely not locost options, but they come from the factory which means they are probably developed for much more than those figures. You could also go through the math equations that will calculate the size of the injectors that you need. I'll see if I can dig those up for you. Hope this helps.

Beags

[Edited on 2/27/2012 by beagley]

Porsche 968 turbo S?

Variant
968 Turbo S

Engine
Front longitudinal inline four cylinder water cooled 8v, KKK Turbo

Capacity
2990 cc

Max. Power
305 bhp (350 bhp for Turbo RS

Stu

[Edited on 27/2/12 by whitestu]

Nissan 1.8CA Turbo, cheap to buy and tune and stage 2 will be circa 265bhp

Dave, have you calculated the fuel flow? I can help you identify the flow and have a list of every Bosch injector and it's flow rate to select the right one if you want.

1999/2002 Saab Aeros (HOT )have the B205r engine, the 205bhp model, I had mine up round 300bhp with the stock injectors.


Froggy will help you out , he is well read on Saab stuff.



http://www.ericsaabsite.com/Upgrades.html

[Edited on 27/2/12 by T66]

Cosworth

I dug up my book Supercharged! by Corky Bell and while you're not talking about forced induction there is a pretty simple calculation that will give you a rough idea of the size injectors that you need. The formula is:

Injector Rating in Pounds/Hour = ( Maximum bhp x .55) / (Number of injectors) @ 100% duty cycle

The problems is that the figure ".55" is the BSFC used for supercharged engines at full load. I did some quick searching, and didn't find a figure for a N/A car. It also mentions in the book that you want your injectors to run at about 80% duty cycle for best effect. So.... if my math teachers were any good.... we have...

(250 bhp x .55) = 137.5, 137.5 / 4 = 34.375 lb/hr, divide by .8 (80% duty cycle) = 49.96875 lb/hr
(300 bhp x .55) = 165, 165 / 4 = 41.25 lb/hr, divide by .8 = 51.5625 lb/hr

So it seems that around a 50 lb/hr injector would be the appropriate size. There are many other formulas, fuel pressure, pump requirements, etc... but I am using this as a "ball park" guess that you can use to get the appropriate size.

PLEASE anyone correct me if I'm wrong!!!

Beags

x10.5 to convert from lb/h to cc/min

That means ~500cc/min

I'm 99% sure the 1.8 turbo engine present in hundreds of different VAG cars can be tuned to beyond 300BHP but still use stock injectors. They only start out at between 150 and 250 BHP as stock, but the increase to 300+ does not involve a change of injectors.

Look at Skoda VRS, SEAT Cupra, VW GTi's of various forms, Audi use it across their range, etc.

cosworth 804's

the saab injectors could be used , it really depends on what you actually need .

you need to size so that at 80% duty cycle your making 300hp ....

would you not use 400cc injectors?

Staying within limits I can confirm from experience toyota 3S-GTE injectors (MR2 turbo, Celica GT4) can do about 280hp at stock pressure (440cc) and 340ish with the later spec 550s in that engine. They are side-feed though.

You can buy some nice Injector Dynamics 1000cc ones for about £100 a piece.

Lotus Esprit S4S or sport 300.

Thanks all, plenty of food for thought.

Another approach, though it would likely work out a little more costly is to use 2 injectors per cylinder in an under and over rail, easy to find 150bhp injectors.
I've read somewhere about it being an advantage since the spray patterns would tend to have smaller droplets and a better fan shape (could just be the internet talking though)

"(250 bhp x .55) = 137.5, 137.5 / 4 = 34.375 lb/hr, divide by .8 (80% duty cycle) = 49.96875 lb/hr "
err, no its
=42.96875 (not 49...)

quote:

---

Originally posted by gremlin1234
"(250 bhp x .55) = 137.5, 137.5 / 4 = 34.375 lb/hr, divide by .8 (80% duty cycle) = 49.96875 lb/hr "
err, no its
=42.96875 (not 49...)

---

SAAB Turbo 'Reds' would be worth a look


Whichever ones you choose in the end make sure they are the right Impedence for the ECU you are using

I ended up with some 525cc (50lb) corvette injectors. They must be z7 or something really tasty. The best thing is you can pick out the best and stick the remaining 4 back on ebay! Made it a cheap way round for me.

Dave, look at me injector uk and ASNU injectors if you're looking for performance. I can put you in touch with Steve to discuss e benefits.

quote:

---

Originally posted by whitestu
Porsche 968 turbo S?

Variant
968 Turbo S

Engine
Front longitudinal inline four cylinder water cooled 8v, KKK Turbo

Capacity
2990 cc

Max. Power
305 bhp (350 bhp for Turbo RS

Stu

[Edited on 27/2/12 by whitestu]

---

Stock Saab reds are good for 280hp at 3bar 80% duty . If your motor takes the same size a set of 630 siemens deka as fitted to most tuned 1.8t vag motors will give good control low down and support 400+ hp no problems . I have run the 870cc version of the same injector with no issues at very low duty .

I've got plenty of reds if you want a set , just cover the postage .

Vaux can easy do it!

Not on reds unless you aren't bothered about maxing the d/c

d/c ?

Duty cycle . The reds are flat out to support 300hp so any knock and there is no capacity left to add fuel under knock conditions .

Duty cycle yep was talking hp wise....me bad.... sorry