[kickster]

I am going to P&P the head the mechanic said I should shave it so I can boost the comp. by 1 point. I am already at 10:1 so after shaving it will be 11:1 or 11.5:1 is this safe? Any performance gain? How does it effect emission? does 94 octane gas satisfy the engine high Comp?
Ps the digi head goes on a ABA bloack

 

[john green]

Re: 11: 1 comp safe or not? (kickster)

I don't know if I would try and achieve a full point......maybe a grp A gasket. 94 might struggle above 11.1:1

 

[phatvw1]

Re: 11: 1 comp safe or not? (john green)

quote:[HR][/HR]I don't know if I would try and achieve a full point......maybe a grp A gasket. 94 might struggle above 11.1:1[HR][/HR]​

I agree... Sport Compact Car recently did a 2.0l Nissan Sentra with compression around 11.0 or 11.5:1 and they were worried about detonation on high loads running on regular pump gas. They were comtemplating on using some 103 octane gas

.

 

[kickster]

Re: 11: 1 comp safe or not? (phatvw1)

now I am worried!!

 

[phatvw1]

Re: 11: 1 comp safe or not? (kickster)

I'll see if I can find the article...
*edit: June 1998 Sport Compact Car... I might have it somewhere in my room. problem, no scanner @ home

[Modified by phatvw1, 11:24 AM 11-30-2001]

 

[hoodita]

Re: 11: 1 comp safe or not? (kickster)

You'll gain some horses. Mine is at 11:1 . I dont have a knock sensor and I am running 93 octane and its never detonated.

 

[Vdub Boy]

Re: 11: 1 comp safe or not? (Oreganoflow)

My current ABA setup is running at least 11:1 compression. No knock sensor like Hoodita and most importantly no knocking or pinging as well.
I always use Petro Canada 91octance gas.

 

[kickster]

Re: 11: 1 comp safe or not? (Vdub Boy)

cool so I will shave the darn thing, we have 94 octane gasoline here. I also have KS.

 

[phatvw1]

Re: 11: 1 comp safe or not? (kickster)

Ok, then you can run 11.0:1. The detonation risk is probably dependent on head design too...

 

[Vdubs]

Re: 11: 1 comp safe or not? (kickster)

You should have no problem if the engine is set up to suit the increase in compression. Increase the fuel octain with some booster, if you are running a knock sensor you will probably loose all the gains if you don't increase the octain.
Oh yea, don't forget it becomes on interference engine, kissy kissy.


[Modified by Vdubs, 3:24 PM 12-1-2001]

 

[kickster]

Re: 11: 1 comp safe or not? (Vdubs)

well my car is a digi and comes with a KS, I cant even remove it since Computer gets signal from it.

 

[Broke]

Re: 11: 1 comp safe or not? (Vdubs)

quote:[HR][/HR]...Oh yea, don't forget it becomes on interference engine, kissy kissy.

[Modified by Vdubs, 3:24 PM 12-1-2001][HR][/HR]​

You mean it becomes an interference engine by adding the ABA block to the 1.8 head? I didn't think my old 1.8 8V was an interference engine...so why would bolting on a different block make any difference?
The piston tops still come to the top of the block, right, same place the old 1.8 pistons stopped, only the 2.0 pistons go down into the block further before coming back up

I know Andrew Foss made his engine an interference type by sticking in a big cam, changing how far down the valve faces go, but with the stock cam, the valve faces should move no further down than before, so just bolting a ABA block in doesn't mean it is an interference engine, right? You cave to add a big cam to make it hit....I thought.
I also thought I read somewhere (either form you or JeffB, I thought), about the 1.8 8V engine, and it was an interference engine.
I don't know....I confused myself now

Broke

 

[Vdubs]

Re: 11: 1 comp safe or not? (Broke)

The data books say it's an interference engine but i've never known one to bend a valve and i don't think it's happened to anyone one Vortex, the valves only just clear the piston so by fitting a cam the valve opens further but shaving the head lowers the valves bringing them closer to the piston and could make it an interference engine.

 

[Broke]

Re: 11: 1 comp safe or not? (Vdubs)

Oh yeah...shaving the head would do it too

So, in the books, the 8V is listed as an interference engine...and I thought somebody once said they checked the books, and it states a 16V is not an interference engine, when in fact, is sure as heck is? Or am I just confused again.
Maybe the book is just backwards? I assume it speaks of the engine in the factory condition...no big cam or decked heads, and a 8V seems a non-interference design, and we all know a 16V will bend valves, so it is just backwards?
Broke

 

[Ted]

Re: 11: 1 comp safe or not? (Broke)

Considering a stock 2.0 16v has 10.8:1, going a little more to 11:1 shouldn't cause much problems even if it's going to be on an 8v. Just use 92 octane...

 

[Vdubs]

Re: 11: 1 comp safe or not? (Broke)

Well the book states the 16V is, in my experience it is and most of the people on Vortex (from what i've read) with a 16v have bent valves after a cambelt went, I think it was 16Vnotchback that escaped without damage.

 

[Andrew Foss]

Re: 11: 1 comp safe or not? (kickster)

yes kiddies...beware...big cams bend valves....shaving the head would do the same i would think.
-andrew

 

[rebel_eye]

Re: 11: 1 comp safe or not? (Andrew Foss)

How much HP is this good for ?

 

[DonL]

Re: 11: 1 comp safe or not? (rebel_eye)

Also keep in mind that with higher compression, it would be a good idea to make sure the car runs cooler. Lower temp `stat and fan switch, with a clean radiator, fresh, properly-mixed coolant. High temps and heavy loads with high compression isn't always conducive to longevity...