Huge deck height – what effect?

[Fastbrit]

OK, here we have an interesting situation. 84 x 94 motor has CE heads with 40cc chambers, FK-10 cam. Not much leeway to open out chambers due to flycut. Pump gas street motor – want CR down to 10 or so. Never run an engine with more than 90thou (2.25mm) – and that was a turbo. What would be the effect of running 3mm (120 thou) or more? Yes, obviously less power, but what else? Is it possible? Hot? Cold? Assuming around 200+bhp on present 12.9:1 CR, what would you expect with large deck height?

Jim? Anyone?

(Mark Herbert, where are you when we need you... sniff. )

[Martin Greaves]

Why not cut the cylinder down or just put a turbo on it.

[Fastbrit]

Why not cut the cylinder down or just put a turbo on it.

The current deck height is 55thou, so looking to add deck, not remove it. And turbos are for race cars... Never quite sure why your car has one, tough!

[Frank LUX]

Why not cut the cylinder down or just put a turbo on it.

The current deck height is 55thou, so looking to add deck, not remove it. And turbos are for race cars... Never quite sure why your car has one, tough!

Nice one Keith...

Frank

[Martin Greaves]

Yes sorry just read it back also I'm with you i dont know why i got a turbo on my car to.

[Martin Greaves]

Why not cut the cylinder down or just put a turbo on it.

The current deck height is 55thou, so looking to add deck, not remove it. And turbos are for race cars... Never quite sure why your car has one, tough!

Nice one Keith...

Frank

You can shut up to.

[Frank LUX]

Why not cut the cylinder down or just put a turbo on it.

The current deck height is 55thou, so looking to add deck, not remove it. And turbos are for race cars... Never quite sure why your car has one, tough!

Nice one Keith...

Frank

You can shut up to.

Sorry,

No Comprede...Amigo...!!!

Frank

[Jim Ratto]

OK, here we have an interesting situation. 84 x 94 motor has CE heads with 40cc chambers, FK-10 cam. Not much leeway to open out chambers due to flycut. Pump gas street motor – want CR down to 10 or so. Never run an engine with more than 90thou (2.25mm) – and that was a turbo. What would be the effect of running 3mm (120 thou) or more? Yes, obviously less power, but what else? Is it possible? Hot? Cold? Assuming around 200+bhp on present 12.9:1 CR, what would you expect with large deck height?

Jim? Anyone?

(Mark Herbert, where are you when we need you... sniff. )

I think you're going to have a what I refer to as a "stale" burn...  meaning the fuel/air vapor will compress, but it ain't going to be the nice "volatile" mixture as if you had less deck. Hate to ask, but can the heads be semi-hemi'd?
Or maybe a heron type chamber in piston?
I've run .100" in a few Bus engines and they actually had some balls to them but they didn't have the "snap" of a tight deck motor.
Or yeah, trim tops of cylinders and semi hemi heads. On some motors I have .040" taken off top to remove chamfer and create a wider firewall for head sealing.
see ya in June  

[Zach Gomulka]

Lots of deck will make the engine more prone to detonation. I'd also rather keep the combustion in the aluminium head instead of the iron cylinder. You can have the pistons dished, but I'm not sure how many CC's you can get out of them without weakening them. My math shows 10.8:1 with an extra 10cc in the pistons. What type of pistons are they?

[team97]

Keith, you could add a .040 copper head gasket to help lower the CR. I use them and don't have a problem with the nitrous.

[Jim Ratto]

Keith, you could add a .040 copper head gasket to help lower the CR. I use them and don't have a problem with the nitrous.

I've gotten a headache from whipits

[team97]

Keith, you could add a .040 copper head gasket to help lower the CR. I use them and don't have a problem with the nitrous.

I've gotten a headache from whipits

Off topic, this isn't what did you have for lunch.

[Jim Ratto]

no pasta

KS on a serious note (Honestly) The Berglar(I am not trying to start crap ) ran a huge deck with those old welded roundey-roundy VW heads on it.... I think they were like 30cc and the motor had .150+ deck if I remember... I just remember turning motor over to see "wow is thing really at TDC?!  "
That car ran "ok" when I drove it. Didn't it go 13's in its low CR setup? 

[Fastbrit]

Well, just working it out, 3.5mm deck (0.140in) deck would give 10.08:1 CR. There are small valve pockets in the pistons, too, so I guess that would help get it down a shade more. 0.150in deck gives 9.83:1...

Dave Greiner on the 'other' forum reckons that once you get over .070 deck, there isn't much difference. Love to see it on a dyno.   

[Bill Schwimmer]

Just bite the bullet and put a set of Wedgeports on it and all will be right. You can use the CE's on your new Canadian 356 project. 

[richie]

Well, just working it out, 3.5mm deck (0.140in) deck would give 10.08:1 CR. There are small valve pockets in the pistons, too, so I guess that would help get it down a shade more. 0.150in deck gives 9.83:1...

Dave Greiner on the 'other' forum reckons that once you get over .070 deck, there isn't much difference. Love to see it on a dyno.   

2 words

"Split cylinders"

Dish the pistons,which brand are they? wisecos you can get 12cc and mahle 7/8cc both safely,bergs do an excellent job and quick turnaround,just bring them with you in a couple of weeks and I am sure they will be done ready for your return home 

you need to measure the notches as well,i have had 3cc in mine

Oh and my old N/A engine with comp elims was 10.2 and was perfectly drivable and batesys is 10.5 I think,maybe more and gets plenty of milage

cheers richie,uk

[ugly duckling]

i agree with the current and younger fast brit. put 10cc in the piston. or you could listen to bill and put on some of those port voluem from hell heads but if you and bill where to line up and run it you whould probebly still be looking at his tail lights  . gotta mess with ya now and again OLD FAST BRIT .UD.

[nicolas]

hail to the new fast brit! 

couldn't resist.

interesting to see that the way the volume of the chamber is achieved plays such a big difference as well.

[BeetleBug]

Keith, why don`t you keep the compression as is, buy a Holley black pump, rejet your carbs and convert your car to E85? It`s cheaper than gasolin, you will run cooler and you will doing nature a favour at the same time.

Best rgs
BB

[Fastbrit]

Keith, why don`t you keep the compression as is, buy a Holley black pump, rejet your carbs and convert your car to E85? It`s cheaper than gasolin, you will run cooler and you will doing nature a favour at the same time.

Best rgs
BB

OK, after consultation with my mentors, Dave and Judy Kawell, I have made a decision.... So, see you at EBI!

As for E85, the nearest source of it tome is over 100 miles away – you can't buy it at many places over here. I also dispute its benefits regarding the environment – turning fields that produce food over to fields that produce fuel is difficult to defend on environmental grounds!

[drgouk]

Hi Keith,
           Would you mind sharing the kawell's advice? I am just interested in what they reccomended, not to disagree.
What do you think about running the comp "E"s on the street? in my latest project 2232, i was thinking of doing the same. 10.5:1 comp, fk87 or fk45-46, It will only see limited street miles


Thanks

David