In the beginning.....

2.5 Litre Capacity
Closed deck block
Strong Liners
New Pistons
New Rods
New Crank
Racing line Billet Inlet Manifold
4 x 54mm Throttle Body Kit
Garrett Turbo
8 Injectors (4x550 & 4x650)
Racing line Parallel Fuel Rail kit
Racing line Rotated Down Pipe
Racing line Rotated Up Pipe
Racing line Exhaust System
Headers
Re-Profiled Cams
Vernier Pulleys
Ported Heads
Reshaped Inlet Valves
Billet Flywheel
Billet Pulley Set
Paddle Clutch
6 Speed Gearbox
DTA P8Pro ECU
NX Express Direct Port NOS Kit (Jet Size To Be Determined)
NX Express Intercooler Spray Bar & 10lb Bottle
Large Front Mount Intercooler
Larger Radiator

 

 

Very nice Couple of questions...

Have you found a source of new cams that will still utilise VVT?

Vernier pulleys seem like a good idea but I have also had difficulty finding these for anything with VVT

Good luck with the project & please keep us updated

 

also.. I assume wasted stem on inlet only.

David

 

The VVT is on the cam pulley. Replofiled cams will still retain all the VVT functionality.

Paul

 

what?

 

Replofiled cams are the next big thing....

The sti 7/8 cams are I beleive very hollow, made with sintered lobes and ends on what starts out as a forged tube.

I got some cams reprofiled (old technology) by Piper cams, and it cost about £280-300 all in (part of bigger bill so unsure). But if you got for extra lift, you will need new springs and retainers, as the standard ones can't cope with any useful extra lift. Replacements are usually smaller gauge wire, doubled up to give great preload and nose load, combined with greater available compression.

The US Sti followers are solid, with integral shim. You can get replacement ones, unmachined, or add shims. Not sure on the UK/Jap sti 7/8 though, possibly the same, or maybe seperate shims. You will need to do something as the reprofiling removed material from the base circle to give more overall lift/duration.

That said, I am not sure it's necessarily worth doing the cams on the the Sti 7, as the AVCS does give you somthing extra over a standard head. That said, you may feel that the extra flow offere by more lift is worth the trouble, even if you keep the duration very similar. There are 2 ways of looking at it. Getting more power from low duratio cams, or getting acceptable idle and off boost performance from wild cams, what's your poison?

I think sti cam duration is about 256º with about 8.35mm lift. I got 264º Duration with 10.something lift, which gives a useful increase in flow with ported heads.

Looks like I will get back some space in the garage in the next few months, I still need to round up a few bits for my engine, like idle control doodads.

Paul

 

Conrad & Paul many thanks for the replies

I have looked around for cams that may suit, including companies like JUN, but have not come up with a proper solution yet. There still seems to be lots of questions on the GDB / VVT situation when it comes to availability of good solutions - just a little early yet I guess

The guys on NASIOC have posted quite a bit of info.

Apparently version 6 cams will fit or can easily be made to fit with the correct bearing choice but then no VVT

The lack of quantified info, such as how much bottom end loss you would experience with 264 or 272 cams, makes the decision more complicated.

Looking forward to seeing how your project develops

 

do a search on avcs on nasioc theres a fair bit of info.

David

 

Why don't you wait till I have tried the 264 cams on the 2.5?

Alternatively, get in contact with Adam, he is running a longer duration, lower lift cam than mine, and his certainly didn't lack bottom end.

THe real question is, what sort of motor do you want? If you can honestly answer this, then it's a relatively simple matter to sort out.

paul

 

Conrad, If you feel like this is hijacking your project thread then I will gladly move it to somewhere else - just shout

Paul, I did email Adam about his project but he didn't reply - I don't have a problem with this as I appreciate some info may not be for general consumption. I don't particularly want 500 or 600+ & only because I can't afford the bills that would go with it

What sort of timescale do you plan for your build?

I have a fair idea what I want - a GDB car that feels FAST like a 300+bhp GC8 feels. In figures, a solid 450/400 seems like a good target - as set by JB - with lots of bottom end power including good off boost performance. I would certainly sacrifice top end power at 6k to 7k to gain a lot more than I currently have at 3k to 4.5k as this is where the car will generally be

I am confident that RCM can provide it but it is difficult for me to sort out the fine detail like whether to go for new cams & head porting or not. A 2.5 build with custom rods & pistons and a new ECU could easily achieve what I want but it is so far from where I am now at 294bhp / 302ft/lbs that I cannot imagine how it will feel using a "seat of the pants power meter" IYSWIM The lack of info on proven GDB 2.5l builds adds to the confusion



[Edited by Callum Ferguson - 11/12/2003 3:17:23 PM]
really should be able to spell properly by now!

[Edited by Callum Ferguson - 11/12/2003 3:24:49 PM]

 

I am hoping that the extra 1/2 litre overcomes bottom end losses due to higher lift / duration cams. I want to avoid "removing" the VVT which is why I went to the trouble of sourcing an STi 7 engine. Until I / We get the heads in bits I can't really say what we'll end doing cam wise, Hopefully you will have run your engine by then Paul? JUN do have cams but they aren't available to the public yet Kent have looked into it but gave up because they thought the cost of the finished cams would not be worth mass production at around £1200 / set Much work to do before I get to that stage

Conrad

PS: More worried about destroying the gearbox at first 1/4 mile launch

 

reprofiling cams really isn't rocket science. What I mean, is you get back the same cams you send, except the lobes come back a different shape.

Kent also do billet cams, made from a blank, but IMO this is inferior to the hollow standard cams.

If you need your Sti cams reprofiled, I can get it sorted out.

Paul

 

Thanks Paul Done a fair bit of research on new cams that are available and that is ZERO. I believe my cams are hollow but filled with sodium. Currently investigating a proven cam option that works well from Subaru with AVCS (SPEC C Items )I may have sourced a supplier for some but if that falls through I could be intouch.

Callum, no worries about hijacking the thread, wait until I get my car back next week, should be over 400 may suit the type of package your looking to get and then we can discuss what mods you need.

 

I don't know if the cam itself is filled with sodium, there isn't a reason for it. The sodium in the exhaust valves is for heat transfer from the valve head up the shaft and into the guide/head assembly.

Subaru quote a 1.4kg saving from each side of the engine with the hollow cams.

I get the impression you just want to pay some money and get a shiney box of new things that drop into place. At this point in time it wont be so simple, but you can get what you want if you are prepared to do a little legwork.

I don't know why you would be after a 'product'. What you need to concern yourself with is the profile. Perhaps Kent have said they can't supplyy you with new cams, but you can profile a wooden spoon if you want, it really makes no difference if it's a hollow, AVCS equiped wooden spoon or not. You can go to someone like Piper cams, and specify a duration and lift, and also an offset. That means you can have the cams timed differently to factory timing in their default position, without having to change the pulleys. Send them your cams, 10 days later your cams arrive back with a new profile, simple as that. And obviously as they are your own cams, they will still be AVCS compatible.

The valve train parts can be more tricky, but they do exist, I have some myself. It's then just a case of finding someone competent enough to build the heads with your profiled cams and collection of valve train parts.

Are you worried about trashing a perfectly good pair of std Sti cams? If you get a reasonably mild profile to start with, there is no reason not to get them re done at a later date if you want to go further.

Paul

 

Cheers Paul, I here what you are saying, I was merely looking for that "drop in" shiny new part as you describe where all the legwork had been done but it would appear it doesn't exist. Subaru has already done the legwork on the SPEC C Items and I dont want to get into the realms of building it, stripping it, building it etc just because I got the cam profile wrong myself. I would like to wait and see how your profile behaves when you get up & running It could give us a good base setting for a new profile or the maybe the same profile.

Conrad

Re sodium filled, I did mean the valves not the cams DOH!

 

I wouldn't have a problem running reprofiled cams as long as there was enough material on the original billet to accomodate the new profile. What I wouldn't fancy is to have the original cams built up by welding prior to the regrind as I know I would forever be wondering about the integrity of the weld.

How do the Spec C cams differ from the STi 7's?

 

Callum,

There is plenty of meat on the phase 2 cams for reprofiling, you could have mucho lift if you want.

Conrad,

I see where you are coming from. but to be honest, the engine you are building isn't the Spec C. You need ot define your ultimate targets, plot the path, then follow it. You must decide what to do with the extra displacement. Do you want to drive a big turbo and make lots of extra top end power, but live with bottom end the same as your 2.0. Or do you want not much more power but more flexibility and response?

The turbo and cams should compliment each other. It's no good going for cams that give excellent mid range but run out of puff at 6000rpm, if your turbo is good for airflow at up to 8000rpm on the boost you want to run, with the capacity you have.

I know of subaru engines running today with around 256, 264, 268 and 272 degree durations. And to be honest none of them are gutless low down.

If you have the time, wait it out, only buy what you need when you need it (ie not like me!). My complete cam and valve train setup cost around the £600 mark, but I suspect it's nearer £650, hadn't had the nerve to add it up!

Properly mapped AVCS has shown to pull the boost threshold down by about 400rpm, so you have that up your sleeve compared to us old skool guys! I would say that you could easily get away with 264º duration, possibly 272º with more lift again. It really depends on what you want out of it.

Paul

 

272 which fools run stuff like that?

David

 

Mikee for a start

 

Paul, the intention for the motor is to make big HP at the top end with the big turbo (when required not all the time)and I would be quite suited if the bottom end was like my 2 litre. So I need cams that will suit that configuration based on mid to top end power???

Conrad

 

callum, came across this by chance, have not receeived an email from you.

Ask anyone on this board, I have no problems talking to those who ask.

try emailing me on adammessulam@hotmail.com.

the 22b.com address gets spammed as I use it for signing up for accounts to try to keep the other emails addresses free.

Will tell you what I can.

 

and another thing.

Much as I woudl love vvt, I have too much torque low down (even accounting for true spool up on the road as opposed to the engine dyno) to destroy the gearbox I am running.

If anything I am hoping for a little lag in order for me to appreciate the high compression off boost nature of the larger capacity engine.

To put it into perspective.

Overlaying my graph against the dyno plot for any standard impreza and it has more torque and more power everywhere despite going on to 567bhp and 561lbft and being sub optimal.

There is more to come but its not going to come from my next engine.

 

Adam, no need to hope; map the delay in. I bet you wont though

Richard

 

HEwon't, but I know someone who will

Had to do it to Trouts 2.33lt. EVEN I got scared when it was hitting 2bar @ circa 3100rpm, so we mapped it to 1.4bar, and still got 409ftlbs @ 3000rpm.

I really don't think low down power is going to be an issue on the 2.5lt !!!

Mark.

 

Adam - thanks for the direct response. I did use your 22B address. It is pointless resending the original e-mail as things have evolved considerably since then. I will send you an updated version over the weekend as tomorrow I aim to encourage domestic tranquility by spending the day with Yvonne. Lots of brownie points are required given the scale of the current scooby project Spec is very similar to Conrad's above but using the US Sti 2.5l block and crank.

The development rate of larger capacity engines is incredible To put things in perspective my current state of tune has 100ft/lbs torque at 3000rpm and the peak is 302ft/lbs at 4900rpm My mapping is not optimum but even so the thought of being able to more than double my 3000rpm torque is very interesting

Hope you get your new engine in soon

 

Your not kidding..

my god I love garrett turbos.. eh conrad

David

 

MMMMMMMMMMMMMmmmmmmmmmm.............

 

The butterflys in the WRX manifold ARE the tumbler vavles. THey encourgae the inlet charge to roll over them into the cylinder increasing atomisation etc.

Paul

 

Thats what I was implying Paul, or rather that the Tumbler assemblies are still there but no butterflies / stepper motors on STi version.