Hemmys - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

40oz · 02-19-2002, 08:46 PM

the KA engine's  pistons as we all know are the weak point but if you put in hemmys, increaseing the psi would this be a good or bad thing. it has a turbo charger on it and i would think that it would over heat and start to run like a diesel. And what is the psi of the stock 93 240sx???

*LanceS13* · 02-19-2002, 08:55 PM

stock 240's aren't turbocharged...only their overseas counterparts (180sx, 200sx, Silvia) are.

but you don't  want  to  raise compression on any turbo engine b/c it'll cause detonation.

misnomer · 02-20-2002, 02:00 AM

Yeah, what he said.

Run like a diesel? Do you mean by sound or by compression ignition? You don't want the compression in a spark ignited engine to cause detonation. That not good. Engine overheating is another issue entirely. Too much boost really only causes a heat issue if you are running consistant high RPMs. Up there you're more worried about blowing shit up.

(Edited by misnomer at 3<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>2 am on Feb. 20, 2002)

DuffMan · 02-20-2002, 02:32 AM

Haha, "hemmys"

I think think the stock 240sx pistons aren't flat anyways.

thewholefnshow · 02-20-2002, 08:01 AM

Hemi's... that is great stuff. 13:1 compression almost minimum. They made hemi heads on one of the hachi roku's a while back... 12.6:1 compression. The most I have ever heard is the s2000 pulling 11:1 having a turbo on stock internals.

Diesels run up to 17:1 compression pretty easy, but they don't use spark plugs they use heat plugs or coils and they only usually spin to about 4000 rpms max (smaller vw engines aren't that low, but trucks and stuff are very low, sometimes as low as 2500) That is why they don't suffer from detonation, and why they can drive underwater (with a valid exhaust outlet above water level)

DuffMan · 02-20-2002, 11:46 AM

Volkswagon TDIs have 19.5:1 compression and are turbocharged.

crazycuban · 02-20-2002, 05:45 PM

TDI's are diesel - it uses the compression to detonate, which is what powers the car.

I don't think you can call pistons "hemis"...they're called domed pistons - only heads with hemispherical combustion chambers are "hemis".

chickenmanq · 02-20-2002, 06:33 PM

Yeah, ditto that crazycuban.

Wholefnshow:  Diesels use glow plugs to start the engine until the fuel can detonate on it's own.  After it starts, the glow plugs aren't used.  The pressure ignites the diesel fuel.  Most diesels only go to 3000 redline.  You can run them higher but it's not needed.  With that much compression and weight to the pistons, high rpms would tend to scatter the engine.

Although, back in the 70's, (I think it was the 70's)Cummins did run a diesel on some oval track (don't remember which series of race) with a 9000 rpm redline and it was leading the whole race and was really close to the end, but it sucked a bolt off the track into the supercharger.  That ended the race and the next race season, surprise, surprise, diesels were banned from that form of racing.  However, Cummins made their point about being able to race diesels and win, so therefore didn't bother trying to sneak a diesel in other races.

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02-19-2002, 08:46 PM	#1
40oz Leaky Injector Join Date: Jan 2002 Posts: 52 Trader Rating: (0) Feedback Score: 0 reviews	the KA engine's  pistons as we all know are the weak point but if you put in hemmys, increaseing the psi would this be a good or bad thing. it has a turbo charger on it and i would think that it would over heat and start to run like a diesel. And what is the psi of the stock 93 240sx???

02-19-2002, 08:55 PM	#2
LanceS13 AutoX Junkie Join Date: Jun 2001 Location: MS Age: 39 Posts: 2,044 Trader Rating: (0) Feedback Score: 0 reviews	stock 240's aren't turbocharged...only their overseas counterparts (180sx, 200sx, Silvia) are. but you don't  want  to  raise compression on any turbo engine b/c it'll cause detonation.

02-20-2002, 02:00 AM	#3
misnomer Nissanaholic! Join Date: Jul 2001 Location: Nevada Posts: 2,293 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, what he said. Run like a diesel? Do you mean by sound or by compression ignition? You don't want the compression in a spark ignited engine to cause detonation. That not good. Engine overheating is another issue entirely. Too much boost really only causes a heat issue if you are running consistant high RPMs. Up there you're more worried about blowing shit up. (Edited by misnomer at 3<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>2 am on Feb. 20, 2002)

02-20-2002, 02:32 AM	#4
DuffMan Post Whore! Join Date: Oct 2001 Location: in a cardboard box Posts: 2,517 Trader Rating: (0) Feedback Score: 0 reviews	Haha, "hemmys" I think think the stock 240sx pistons aren't flat anyways.

02-20-2002, 08:01 AM	#5
thewholefnshow Zilvia Addict Join Date: Nov 2001 Posts: 672 Trader Rating: (0) Feedback Score: 0 reviews	Hemi's... that is great stuff. 13:1 compression almost minimum. They made hemi heads on one of the hachi roku's a while back... 12.6:1 compression. The most I have ever heard is the s2000 pulling 11:1 having a turbo on stock internals. Diesels run up to 17:1 compression pretty easy, but they don't use spark plugs they use heat plugs or coils and they only usually spin to about 4000 rpms max (smaller vw engines aren't that low, but trucks and stuff are very low, sometimes as low as 2500) That is why they don't suffer from detonation, and why they can drive underwater (with a valid exhaust outlet above water level)

02-20-2002, 11:46 AM	#6
DuffMan Post Whore! Join Date: Oct 2001 Location: in a cardboard box Posts: 2,517 Trader Rating: (0) Feedback Score: 0 reviews	Volkswagon TDIs have 19.5:1 compression and are turbocharged.

02-20-2002, 05:45 PM	#7
crazycuban Zilvia Junkie Join Date: Nov 2001 Posts: 526 Trader Rating: (0) Feedback Score: 0 reviews	TDI's are diesel - it uses the compression to detonate, which is what powers the car. I don't think you can call pistons "hemis"...they're called domed pistons - only heads with hemispherical combustion chambers are "hemis".

02-20-2002, 06:33 PM	#8
chickenmanq Zilvia FREAK! Join Date: Nov 2001 Posts: 1,000 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, ditto that crazycuban. Wholefnshow:  Diesels use glow plugs to start the engine until the fuel can detonate on it's own.  After it starts, the glow plugs aren't used.  The pressure ignites the diesel fuel.  Most diesels only go to 3000 redline.  You can run them higher but it's not needed.  With that much compression and weight to the pistons, high rpms would tend to scatter the engine. Although, back in the 70's, (I think it was the 70's)Cummins did run a diesel on some oval track (don't remember which series of race) with a 9000 rpm redline and it was leading the whole race and was really close to the end, but it sucked a bolt off the track into the supercharger.  That ended the race and the next race season, surprise, surprise, diesels were banned from that form of racing.  However, Cummins made their point about being able to race diesels and win, so therefore didn't bother trying to sneak a diesel in other races.