karl. Posted January 9, 2014 Share Posted January 9, 2014 Hi there, Im looking about going forged, and while im at it make my engine a bit higher compression to aid spool. Currently its on a standard head, not skimmed or anything. What size of head gasket do you recommend etc? Currently on a td04 but wouldnt mind going to a td05 if the spool times can be kept roughly the same? Not really clued up on this but can it be done? Quote Link to post Share on other sites
AdamB Posted January 9, 2014 Share Posted January 9, 2014 (edited) Skim the head , use flat top pistons (although I wouldn't recommend), use a thinner headgasket 0.6mm is ideal. I highly doubt you will ever get a td05 to spool like a td04 unfortunately. If your looking for more power with around the same spool as td04 then look at dual ball bearing turbo's, but they are expensive. Getting the compression ratio to around the 8.5:1 mark will yield a nice gain. No reason why you can't run 9:1 but I doubt there's enough material in the head to be able to do this without having the valves bashing the pistons at full lift. Edited January 9, 2014 by AdamB Quote Link to post Share on other sites
Turk Posted February 3, 2014 Share Posted February 3, 2014 Many ways of increasing compression. But you can also go for a 5e block. Will decrease spool up time significantly. I would personally run 9:1 compression. Also i would do it by pistons as its the most safest route. Quote Link to post Share on other sites
Phil Posted February 3, 2014 Share Posted February 3, 2014 Hi there, Im looking about going forged, and while im at it make my engine a bit higher compression to aid spool. Currently its on a standard head, not skimmed or anything. What size of head gasket do you recommend etc? Currently on a td04 but wouldnt mind going to a td05 if the spool times can be kept roughly the same? Not really clued up on this but can it be done? Speak to Chris Carson Karl. He will be able to advise and build for you locally. Phil Quote Link to post Share on other sites
GP82 Posted February 4, 2014 Share Posted February 4, 2014 Here we don't go high C/R to aid turbo spool up spesh on a road car. High c/r is to get a bigger bang, but with better then pump fuel. You have to tune the a/f and ignition advance to build cylinder pressures up quick to aid spool up. Stock c/r for a TD04 is perfect, i would go lower if your bolting a TD05 on if you want to get the max out of the setup. With a high c/r you will eventually find out that you are boost limited because detonation will start to occur at the higher boost pressures on pump fuel. You make more power per pound of boost then what each full point of compression is worth. It pays to trade off compression for the ability to run more boost on a street driven car on pump fuel. There is nothing wrong with flat top pistons, they actually produce a better combustion flow without interrupting swirl. Quote Link to post Share on other sites
Phil Posted February 4, 2014 Share Posted February 4, 2014 (edited) Here we don't go high C/R to aid turbo spool up spesh on a road car. High c/r is to get a bigger bang, but with better then pump fuel. You have to tune the a/f and ignition advance to build cylinder pressures up quick to aid spool up. Stock c/r for a TD04 is perfect, i would go lower if your bolting a TD05 on if you want to get the max out of the setup. With a high c/r you will eventually find out that you are boost limited because detonation will start to occur at the higher boost pressures on pump fuel. You make more power per pound of boost then what each full point of compression is worth. It pays to trade off compression for the ability to run more boost on a street driven car on pump fuel. There is nothing wrong with flat top pistons, they actually produce a better combustion flow without interrupting swirl. Yup, high c/r for better dynamic compression. As GP82 says its not less laggy - its less lazy. For street car/drag car/straight lines lower comp and more boost will get you the same results with less hassle. personally higher than stock compression is a drive i would enjoy with a td04 pump fuel and 1.0-1.2bar ish. you could go higher boost or bigger turbo but you would start needing water meth or race fuel to get yourself a tune thats pre ignition free. Phil Edited February 4, 2014 by Philm Quote Link to post Share on other sites
AdamB Posted February 4, 2014 Share Posted February 4, 2014 Flat top pistons do not work as well as dished pistons in a turbo motor because of the quench area and flat tops retard flame travel, costing power at the crank. It depends on the turbo you use, the more efficient it is a long with an efficient intercooler, the higher you can go on the compression. Temperature is everything really. Quote Link to post Share on other sites
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