Raptor6767
Gold Member
Catcam 403's
- Thread starter TB Rich
- Start date
Stephenvenning
Gold Member
[MENTION=38628]TB Rich[/MENTION] there is a gas flowed head on eBay at the moment, would be perfect for your build I reckon.
http://pages.ebay.com/link/?nav=item.view&alt=web&id=251728495949
http://pages.ebay.com/link/?nav=item.view&alt=web&id=251728495949
TB Rich
Paid Member
I asked a very well respected tuner whom I used to know back when I had a 106 (Sandy Brown), of course he hasn't seen the engine but asked informally how likely it was the manifold could cause it, he confirmed it is possible:
"Yes, it's entirely possible. The stronger scavenging of a tuned exhaust manifold can not only pull more fuel straight out the exhaust on overlap (depending on cam and injection timing), but by virtue of the improved cylinder filling that is likely, the ECU fuelling correction may not be able to adjust quickly enough or fully, or may not be active past a certain throttle opening."
Also look at the facts, the car was healthy and stock making 193bhp on known rollers only the week before.... facts are facts mate
I'd much rather believe it wasn't the manifold, because it would mean I hadn't spent £1800 to destroy my engine! But alas it was
TB Rich
Paid Member
Cheers dude, but not needed for my target bhp, plus I'm at my spent limit! The 403's will yield 230ish which the stock 200 head can do, I'm having the chap check the inlet and exhaust matching etc. To be honest if I wanted more I would go big valves (35mm inlets) etc and approach Sandy via Pure probably. Also your probably at the point then when you want solid lifters etc so I'd be into spending not far off the same again on the top end!! Happy I have a good solid spec now which should be reliable all day up to 7.5/7.8k. Weakest point will be the stock lifters, everything else will do over 8.5k I think.
You were half right re the valves though, the exhaust (iconel's) are still 2-piece (weld higher up away from combustion), but the inlets are forged single piece stainless.... so I was kinda right too
Apparently Supertec guarantee the exhausts not to break or they will pay for the rebuild, in writing with the builder so good enough for me.
Yiannis197
Paid Member
TB Rich
Paid Member
Never heard of them myself. I've had a couple of modified heads before (one was a big valve job), each time the heads were extensively worked and I was provided flow bench results plotting flow against lift.
It's so easy to screw up a head that unless I'm going to town on it and taking it to a well known respected builder I would tread cautiously.
It's so easy to screw up a head that unless I'm going to town on it and taking it to a well known respected builder I would tread cautiously.
Raptor6767
Gold Member
I'm not saying that I'm right but I can't believe that this R3 manifold makes such a difference that it can actually influence AFR that much.I asked a very well respected tuner whom I used to know back when I had a 106 (Sandy Brown), of course he hasn't seen the engine but asked informally how likely it was the manifold could cause it, he confirmed it is possible:
"Yes, it's entirely possible. The stronger scavenging of a tuned exhaust manifold can not only pull more fuel straight out the exhaust on overlap (depending on cam and injection timing), but by virtue of the improved cylinder filling that is likely, the ECU fuelling correction may not be able to adjust quickly enough or fully, or may not be active past a certain throttle opening."
Also look at the facts, the car was healthy and stock making 193bhp on known rollers only the week before.... facts are facts mate
IMHO. [emoji41]
John1006
Platinum Member
think of it this way the standard exhaust/engine/fuelling is designed for that massive cat (2 of) restriction...take that away and it changes everything
as in theory it all needs re-optimising again...no wonder the fuelling goes tits up!
Raptor6767
Gold Member
Fernandez
Gold Member
These guys are well known in the Renault Scene. Jack Kemp who runs the business with his father is a good lad. Their work is top notch and they do know what they are doing when it comes to tuning
rosscoe
Platinum Member
I've not heard of anyone on here running 403's, simply because you can't run them with std pistons. As you point out you need the higher comp maxi pistons.
I do however know of someone who's just built a 250bhp 197 motor using the maxi pistons and the Catcam follower kit amongst other bits.
I'll ask what cams he on as I'm not sure on the full spec.
Can you get the 403's and the maxi pistons quite easily?
looking to do a good engine rebuild for the track car soon.
Raptor6767
Gold Member
Raptor6767
Gold Member
Fernandez
Gold Member
Yiannis197
Paid Member
Looking forward to seeing all these NA builds, I haven't seen anything interesting going on in here for quite some time..
rosscoe
Platinum Member
