carl0s Posted March 6, 2007 Share Posted March 6, 2007 I know it's not an exact science, but could somebody please tell me what an off-the-shelf 1.2-ish bar restrictor ring hole measures at? I just replaced my second CAT with a 3" decat and restrictor, and the car is making less boost now than it did with the second CAT in place. 3rd gear (auto) 100mph is seeing about 14psi (0.96bar), so I guess my restrictor is meant to be a 1bar restrictor. How big to I need to make the hole? thanks Link to comment Share on other sites More sharing options...
flukey-lukey Posted March 6, 2007 Share Posted March 6, 2007 I 'think' its about 2 inch diameter, but dont quote me on that... Link to comment Share on other sites More sharing options...
carl0s Posted March 6, 2007 Author Share Posted March 6, 2007 I found this, will have a go and report back. The OP said in the end he fitted a 50.5mm restrictor (that'd be 2inch like you just said flukey), and was hitting 1.2bar. I guess it's really rather exhaust dependant too. Mine's not half as free-flowiing as, say, an RS*R GT2. From memory, 48mm for 1bar, 52mm for 1.2bar. Cheers, Brian. Link to comment Share on other sites More sharing options...
flukey-lukey Posted March 6, 2007 Share Posted March 6, 2007 could also depend on temperatures? although it is pretty chilly where i am so would expect a higher boost reading... hmm, let me know how you get on Link to comment Share on other sites More sharing options...
Chris and Alana Posted March 6, 2007 Share Posted March 6, 2007 RR sizeing is a pain in the arse, I hav a Nur spec R and a 2.5" 1st decat and I was overboosting and getting boost creep with the second cat still in so I put a 2" rr in and got 12 psi so I took it out filed it a bit, measured the size for future reference and put it back in but 7 attempts later I couldnt be arsed measuring the size and eventually got a steady 15psi. Anyway not to helpful but my point is I think its trial and error or in and out if you like until you get it right but what a pain . .. . . Good luck. Link to comment Share on other sites More sharing options...
bolarbag Posted March 6, 2007 Share Posted March 6, 2007 I hit 1.2bar with 1st cat in...I'm planning in goin single in sept is it really worth the hassle to the get the 3inch dp, and all this restrictor ring nonesense for the extra 1obhp its gonna give me? Link to comment Share on other sites More sharing options...
Homer Posted March 6, 2007 Share Posted March 6, 2007 Is it a VVTI carl0s? I beleive they have the same size wastegate as the UK, so you'll never see 1 bar on one without a boost controller Link to comment Share on other sites More sharing options...
carl0s Posted March 7, 2007 Author Share Posted March 7, 2007 It's not a VVTi mate, no. Link to comment Share on other sites More sharing options...
wallis Posted March 7, 2007 Share Posted March 7, 2007 hey bud, ive just had my 94 tt j-spec done (last week) and had a few probs also, but got them sorted out in the end and its awesome now, its running at about 1.1/1.2bar. the only info i got told, was that it's really important where u position the RR & on the diameter size of your exhaust, to where/what size the RR is. my system was hand built by the guys from custom performance, its 3" straight through from the downpipes to a single back box at the rear with a 50.5mm RR where the 2nd cat is normaly......50.5mm has worked out perfectly to 3" diameter pipe placed in that position on that system. when the exhaust was first done, i took the car out with no RR on, and the thing was overboosting, miss-firing, and spluttering at about 4000rpm to 6000rpm....i was lucky i didnt blow up the turbos im told now! so next we fitted a boost gauge and my turbos were like over boosting upto 1.5bar!! I was told the fuel cut off should of kicked in after 3 sec on any boost over 1 bar with a standard set-up & ecu........for some reason it didnt on my supra?? so after that we fitted the 50.5mm RR and it was perfect boosting upto just under 1.2 bar, ive done about 400 miles in the car since with no problems yet(touch wood)! Also u need to fit colder plugs if u have not done so already, i used NRK BCPR7ES which are great and cheap....but need replacing im told every 3-5000 miles, but for under 10 sqid a throw who cares! also i uprated my fuel pump to a uk-spek one. hope that may of helped u slightly mate;) Link to comment Share on other sites More sharing options...
carl0s Posted March 7, 2007 Author Share Posted March 7, 2007 Hi Matthew. Thanks for the advice. I have colder plugs, new fuel filter, walbro pump, boost gauge etc. installed already. I just wasn't sure of the correct size for the ring. I'm close enough to 1bar already so I'll just bore it out a bit once the exhaust has cooled down Link to comment Share on other sites More sharing options...
flukey-lukey Posted May 4, 2007 Share Posted May 4, 2007 how did you get on with this in the end carl0s? Fitted my restrictor ring with double de-cats on a nur spec and only seeing 0.9 bar. The ring itself is a whifbits one which came with the decats from whifbits. Think I'm going to file it down a bit Link to comment Share on other sites More sharing options...
carl0s Posted May 4, 2007 Author Share Posted May 4, 2007 how did you get on with this in the end carl0s? Fitted my restrictor ring with double de-cats on a nur spec and only seeing 0.9 bar. The ring itself is a whifbits one which came with the decats from whifbits. Think I'm going to file it down a bit The only files I had were next to useless. Apparently you need to use a 'bastard cut half-round file'. Bastard cut means it's really rough or something Or, do what I did... I used one (actually, about five) of those grinding stone bits that go in the end of a drill. It ate through them pretty quickly but they were only a cheap set anyway. I can't see how you could do it without a vice though. Thank god for grandads and uncles Link to comment Share on other sites More sharing options...
r1george Posted May 5, 2007 Share Posted May 5, 2007 I made my own RR and took advise from the lads on the forum, so I started with 50mm which gave me a 0.9 - 1 bar, I machined it out to 52mm and am now getting a steady 1.1 bar but as people have mentioned it may have something to do with how restristive the rest of the exhaust is. I have a full mongoose fitted which even with full decat isn't very loud so i'm guessing it's probably more restrictive than the jap stuff. hope this helps:) Link to comment Share on other sites More sharing options...
Armin Posted May 5, 2007 Share Posted May 5, 2007 a little OT what kind of performance can you expect with this mod? free flowing all the way and a RR. Link to comment Share on other sites More sharing options...
SBDJ Posted May 6, 2007 Share Posted May 6, 2007 Is it a VVTI carl0s? I beleive they have the same size wastegate as the UK, so you'll never see 1 bar on one without a boost controller I've had to put a restrictor ring in my UK, I was making > 1 bar with no boost controller Link to comment Share on other sites More sharing options...
flukey-lukey Posted May 6, 2007 Share Posted May 6, 2007 Thought on this please... I have a blitz nur spec, whifbitz decats and RR, was making 0.8 bar at first, then filed the RR down a bit and made nearly 1bar. Then I took the RR out completely and made a steady 1.1bar. Maybe I'm leaking a bit of boost somewhere? intercooler pipes maybe? Link to comment Share on other sites More sharing options...
styggen82 Posted September 3, 2007 Share Posted September 3, 2007 Is it a VVTI carl0s? I beleive they have the same size wastegate as the UK, so you'll never see 1 bar on one without a boost controller Is this true? can someone confirm this? Link to comment Share on other sites More sharing options...
styggen82 Posted September 4, 2007 Share Posted September 4, 2007 Is this true? can someone confirm this? anyone? gonna fit my new downpipe tomorrow and removing both cats...... vvti 98 mod TT Link to comment Share on other sites More sharing options...
chrisbilling Posted September 4, 2007 Share Posted September 4, 2007 Is it a VVTI carl0s? I beleive they have the same size wastegate as the UK, so you'll never ee 1 bar on one without a boost controller Hi Homer, Just edited my profile with address details, can you send me a membership pack. Thanks Chris Link to comment Share on other sites More sharing options...
Dazzi Posted September 5, 2007 Share Posted September 5, 2007 A little but you guys that have fitted a restrictor ring, does it reduce exhaust noise or just boost? Link to comment Share on other sites More sharing options...
supraguye Posted September 5, 2007 Share Posted September 5, 2007 Is it a VVTI carl0s? I beleive they have the same size wastegate as the UK, so you'll never see 1 bar on one without a boost controller Homer, Is this true? I have a double de-cat on my 98 TT and it currently hits fuel cut. Gonna get rid of the fuel cut soon and would like to know whether I need to fit a 1.2 bar restrictor ring. Thanks Dudley Link to comment Share on other sites More sharing options...
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