JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 I mean can't you just buy new turbos, and keep the manifolds etc? You might have to alter the downpipes, intakes etc a little. But the HKS turbos were generally based on Garrett units, so it shouldn't be too difficult. am assuming though that the issues are being caused by an ancient turbo design. Ohhh... Well yes I'm sure I could and as you say there might only be a bit of modification involved, but I'm no mechanical whiz so would have to pay for it all to be done, and if I was going to do that I'd rather just go single. Seeing the spool rates makes me jealous. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 Drive something like Wes's single and you you will be advertising those twins within the hour afterwards... Area under the curve is what it's all about for a fast road car. Trouble is, high compression, direct injection turbo engines have moved the game on apace, which is why people drive the current GTR and are instantly hooked... Diesel torque, petrol rev range.... Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 7, 2015 Share Posted July 7, 2015 What a truly dreadful power curve for a road car! Years and years ago someone on the forum had an HKS twin turbo kit on a really nice Supra, and he asked me to drive it on some airfield track day. I forget where it was, but long straights. It was, even in that environment, just so laggy as to be hopeless. On the road? Waste of time, a small single, even stock sequentials, would leave it for dead on a country road. Christian's black one, you spent ages bleeding the brakes as well Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 I set fire to them I think.... He didn't realise they had two nipples per caliper, ASP or Brembo calipers I think. He was a bit worried when we were at about 120MPH and I said, "Hold on, we have to make a little detour, no brakes...." Luckily there was a convenient chicane to bypass and the handbrake was fairly effective, used with the gears. I hate pushing other peoples cars hard! Just realised I have a photo of his car on my drive, dated 28th of May 2001! Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted July 7, 2015 Share Posted July 7, 2015 Ohhh... Well yes I'm sure I could and as you say there might only be a bit of modification involved, but I'm no mechanical whiz so would have to pay for it all to be done, and if I was going to do that I'd rather just go single. Seeing the spool rates makes me jealous. And as I was explaining before, with the right set of turbos you should have a faster spooling car than an equivalent single. The beauty of singles is that they simplify the setup, and are therefore more likely to be reliable. Lighter too. What are your power goals? Quote Link to comment Share on other sites More sharing options...
Supraleeturbo Posted July 7, 2015 Share Posted July 7, 2015 I think you may be able to send them Off to Owen developments and have them rebuilt with the dbb and billet enturnals that would make them spool faster Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 I had my HKS Twins rebuilt by Owen Developments. They took the turbos and rebuilt them as OD3071HTA. I had the smaller housing on mine as well, and with the VVTi, it actually made it a perfectly decent setup. Cost me around £1700. The biggest issue about buying turbos to fit is the T25 flange and the 5 bolt pattern. If you fancy a project, you could always rip off the HKS flanges and weld on some nice V Bands and open up the choice of turbos. EFR6758's Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 Drive something like Wes's single and you you will be advertising those twins within the hour afterwards... Area under the curve is what it's all about for a fast road car. Trouble is, high compression, direct injection turbo engines have moved the game on apace, which is why people drive the current GTR and are instantly hooked... Diesel torque, petrol rev range.... If anyone has a 600hp+ single near Cambridge and they'd like to take me for a spin so I can see what it is like, then please feel free and drop me a PM And as I was explaining before, with the right set of turbos you should have a faster spooling car than an equivalent single. The beauty of singles is that they simplify the setup, and are therefore more likely to be reliable. Lighter too. What are your power goals? I understand. I was told before and during having twins installed that they are less reliable, slower to spool and overall just more 'oldschool' than any modern-day Garrett or Precision. Power goal wise, for now I'm not wanting to push anymore than 700hp as I don't have the funds for a fully built engine. I'm sitting at approximately 600hp at the moment, and with 264 cams plus some better mapping (the current map is rubbish) I'm hoping to push 650. The thing is, what kind of twin turbos are on the market which are fast spooling? I was under the impression parallel twins will almost always take longer to spool than any equivalent single, purely because there's two turbos to spool instead of one? Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 I had my HKS Twins rebuilt by Owen Developments. They took the turbos and rebuilt them as OD3071HTA. I had the smaller housing on mine as well, and with the VVTi, it actually made it a perfectly decent setup. Cost me around £1700. The biggest issue about buying turbos to fit is the T25 flange and the 5 bolt pattern. If you fancy a project, you could always rip off the HKS flanges and weld on some nice V Bands and open up the choice of turbos. EFR6758's What were the spool rates before and after the rebuild? And did it have any affect on power? And that would be a nice project to do - if I had nearly enough mechanical experience to even attempt it Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 What were the spool rates before and after the rebuild? And did it have any affect on power? And that would be a nice project to do - if I had nearly enough mechanical experience to even attempt it My turbos were tired before the build, but afterwards, I gained 70bhp at the same boost and around 500-750rpm spool. I was getting full boost by 4k, but positive boost built nicely from 3200 onwards. Very progressive, very nice. I made 500 at 1bar, 644 at 1.4bar. Turbos would do 2bar, but my exhaust was restrictive. With a 4", it's a 900bhp setup. Quote Link to comment Share on other sites More sharing options...
chazuk Posted July 7, 2015 Share Posted July 7, 2015 I think people get far to caught up in dbb/billet/gen2 etc on the street the noticeable difference is naff all from a journal bearing it just means you can not put billet ,dbb,gen2 in your signature, only have to looks at James with his gen 1 journal 6266 and the result from that also saw a thread on supraforums saying the same thing think it only really came into any difference worth noticing on the large frame turbos Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted July 7, 2015 Share Posted July 7, 2015 The goal for my single build will be circa 550hp, and I'm going with a single Garrett GTX3576R, and I would fully expect it to hit full boost at just over 3000rpm in the low gears on my vvti. It should comfortably do 600 though if you want to push it further than me. Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 My turbos were tired before the build, but afterwards, I gained 70bhp at the same boost and around 500-750rpm spool. I was getting full boost by 4k, but positive boost built nicely from 3200 onwards. Very progressive, very nice. I made 500 at 1bar, 644 at 1.4bar. Turbos would do 2bar, but my exhaust was restrictive. With a 4", it's a 900bhp setup. Now after hearing that it is very very tempting indeed... £1700 you say? Did you have the .61a/r exhaust housings? Because that's what I have but anywhere above 1.4 bar and they will surge when trying to come onto full boost. Think the housings are choking them higher up the rev range. Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 The goal for my single build will be circa 550hp, and I'm going with a single Garrett GTX3576R, and I would fully expect it to hit full boost at just over 3000rpm in the low gears on my vvti. It should comfortably do 600 though if you want to push it further than me. That'll be nigh on perfect for a road going Supra. You don't need more than 550bhp in a street-Supra. Bravo. Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 Now after hearing that it is very very tempting indeed... £1700 you say? Did you have the .61a/r exhaust housings? Because that's what I have but anywhere above 1.4 bar and they will surge when trying to come onto full boost. Think the housings are choking them higher up the rev range. I think mine were smaller. But, I had zero surge. I could just nail it anywhere. Sadly, just after I had mine done, I discovered the GT-R Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 The goal for my single build will be circa 550hp, and I'm going with a single Garrett GTX3576R, and I would fully expect it to hit full boost at just over 3000rpm in the low gears on my vvti. It should comfortably do 600 though if you want to push it further than me. 550hp is exactly what I run on a normal day when driving. But without the full boost at 3000rpm. May be worth speaking to Owen Developments about the different possibilities of having them rebuilt. Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 I think mine were smaller. But, I had zero surge. I could just nail it anywhere. Sadly, just after I had mine done, I discovered the GT-R Did you have stock camshafts or 264/272 etc? I've been told 264 cams in mine could make a huge different, but, being a VVTi, cams along with the exhaust valve alone is over £1k. Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 Did you have stock camshafts or 264/272 etc? I've been told 264 cams in mine could make a huge different, but, being a VVTi, cams along with the exhaust valve alone is over £1k. I had 264's in the VVTi. Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 I had 264's in the VVTi. I'm guessing you had the turbos installed when the engine already had 264 cams and therefore can't compare having the turbos with/without stock cams? I'm liking the idea of having them rebuilt. Seems more efficient than just selling the whole kit and buying a whole other kit. Especially because IF I did go single, I'd want a Precision. And those kits cost £££ I just don't understand why my specific spool rate is so horrid. 5500rpm is like drag racing spool rate Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 The HKS GT2835 turbo is a modified Garret GT3071r turbo. The wheels are old and heavy, not that efficient compared to modern technology. Moving to a lighter and more efficient HTA wheel will improve your spool. This is what I had: http://www.owendevelopments.co.uk/product/429/Owen_Developments-Garrett_ODGT3071HTA/ What cams do you have, I know they're 264, but what lift? If you can get a pair of HKS cams for the VVTi, that'll aid your spool, too. I think you should be able to knock 1000rpm off your spool easily. Oh, I forgot to say, I also had a fully build head with 1mm oversize valves. Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted July 7, 2015 Author Share Posted July 7, 2015 The HKS GT2835 turbo is a modified Garret GT3071r turbo. The wheels are old and heavy, not that efficient compared to modern technology. Moving to a lighter and more efficient HTA wheel will improve your spool. This is what I had: http://www.owendevelopments.co.uk/product/429/Owen_Developments-Garrett_ODGT3071HTA/ What cams do you have, I know they're 264, but what lift? If you can get a pair of HKS cams for the VVTi, that'll aid your spool, too. I think you should be able to knock 1000rpm off your spool easily. Oh, I forgot to say, I also had a fully build head with 1mm oversize valves. Ahh I understand much clearer now so the HKS GT2835 kit is actually just parts of modified Garrett turbos, and in order to have them spool quicker they need all the oldschool internals stripped and replaced with more modern-day parts? My cams are totally stock. I am near to having some HKS 264's for the VVTi bought from SRD but not as of yet. I assume the built head aided spool slightly too? Quote Link to comment Share on other sites More sharing options...
chazuk Posted July 7, 2015 Share Posted July 7, 2015 Johnny had smaller rear housings than yours that is were the most gain will be Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted July 7, 2015 Share Posted July 7, 2015 I doubt that rebuilding the twins is gonna improve spool to be competitive with a modern single, seems like a waste of time and money. Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 7, 2015 Share Posted July 7, 2015 I doubt that rebuilding the twins is gonna improve spool to be competitive with a modern single, seems like a waste of time and money. It's about the delivery. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 Lies, all lies, it's about the pose value, admit it! Quote Link to comment Share on other sites More sharing options...
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