Increasing CR? - Turbo Dodge Forums : Turbo Dodge Forum for Turbo Mopars, Shelbys, Dodge Daytona, Dodge SRT-4, Chrysler PT Cruiser, Omni and more!
Engine - General, Exhaust & Induction Topics about the general engine items, exhaust system discussed here & Improving the intake tract - air filter to intake valve.

 
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post #1 of 9 Old 04-23-2006, 08:48 PM Thread Starter
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Increasing CR?

How safe is it to increase compression on a TI? I was considering using two cylinder heads for the Daytona: one milled cylinder head with a regular gasket, then one unmilled/surfaced head with a thicker gasket, for DD'ing and high performance respectively. Eventually, it'll be intercooled, but what can I get away with on unintercooled?
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post #2 of 9 Old 04-23-2006, 09:06 PM
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Everyone is going to tell you that higher compression on a turbo engine is bad. Doing it intentionally, you have to know that will limit your boost output at the least ... worst case is going to be some serious detonation issues .... especially with a non-IC'ed engine.

It'll be a touchy dog.
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post #3 of 9 Old 04-23-2006, 09:10 PM
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Awfull lot of work to keep swapping heads. I ran TBI pistons in my van, didn't know this at the time and ran 12 psi, intercooled. Engine lasted 1 week, I melted it so badly it was done.
ON that note, it can be done but you need to have the cal very finely tuned but the biggest issue is our heads are shit. Honda's and such can get away with it due to better head design.
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post #4 of 9 Old 04-24-2006, 08:25 AM Thread Starter
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Alright. I know 16v cars can get away with it, because of the wedge shape, but I didn't know about our cars. Thanks.
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post #5 of 9 Old 04-24-2006, 11:06 AM
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Built up big block N/A cars on the ragged edge, have found they can raise their C/R ~10%, with out detonation, using Singh's grooves. I have increased mine 6% over stock. No feed back yet because it is not yet installed. http://somender-singh.com/component/...page/Itemid,1/

I know others that also run 8.6 with out problems. What they did to do that I am not sure.
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post #6 of 9 Old 04-24-2006, 12:38 PM
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I read some of the information on that page about groove technology. In the forums section one of the members makes mention of using the groove technology on a dodge 8 valve going into a daytona.....is that person a member of this board as well?
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post #7 of 9 Old 04-24-2006, 06:27 PM
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Read that too ... thing is, our pistons are dished. This mod is stated to be of no use passed 10mm deck clearance ...
Quote:
Originally Posted by fueleconomytips article
The shape of the piston and cylinder head have their greatest affects on combustion efficiency when the piston is within about 10 mm of Top Dead Center (TDC). When the piston is more than 10 mm away from TDC, the cylinder head and pistons are just distant and innefectual walls bordering a large open expanse. So the grooves do their work within this 10 mm range.
... unless I'm misunderstanding something this mod is useless without flat top slugs for starters.
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post #8 of 9 Old 04-24-2006, 07:54 PM
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just add more boost
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post #9 of 9 Old 04-24-2006, 08:41 PM Thread Starter
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Well, I wasn't planning on raising CR for top-end power LOL. I was hoping to improve partial-throttle responce. However, I've read an article in Popular HotRods about CR as well as how racing motors are built for high compression. I was thinking similar methods could be used for mild compression (8.6 like you mentioned) and they spoke of coatings and certain techniques to help bear with the heat. This was on a 2v/cyl head, after all. I dunno how radically different non-wedge heads are. I guess I'll simply just go by what you guys say, as I don't know these motors that well...
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