ty_ty13

iTrader: (42)

just curious how high a compression some of you 9 second are running and actually how many of you there are...

i did my formula last night to check my CR and i'll be damned if im not about 7.9:1 CR.... im thinking about using some ET 255 heads milled to about 58cc and hitting about 9.0-9.2 and still using this little D1 then maybe next year slapping a big blower on there (f1r)...

Pro Stock John

iTrader: (34)

I was 8.0:1, YSi, and went 144mph at 18psi with no real work on the tune from when the car was dynoed. I probably could have added a lot of timing and hit 147mph or more pretty easily... I ran 19-20 degrees of timing with C16 which was beyond safe.

cablebandit

iTrader: (37)

my turbo car is 9.3:1 KP was around the same...dunno what he is with the AFR heads

smokinHawk

iTrader: (48)

id keep the CR ratio at the 7.9 or maybe use a slightly thiner gasket to get 8.0-8.3 and run more BOOST

ty_ty13

iTrader: (42)

what size blower would you reccomend for getting around 1k hp or lets say into the mid 5's in the 8th in a 3500# car

kp

iTrader: (34)

I wouldnt, unlike a turbo you start hitting a brick wall with bigger blowers and an 8 rib belt. Ask PSJ..

In reality one point of compression isnt going to make huge difference, unless you are limited by the size of the blower then it makes a good difference. If it was that easy to eliminate detonation dropping a point or making 100 more hp by raising compression a point, that would be awesome but it doesnt work that way - unless you are limited by turbo or blower size.

cablebandit

iTrader: (37)

i am happier at 9.3 than i was with the 8.2 i had. Car is better off boost and it gives my turbo more room though it will require more octane to max it out. I saw it working for KP so i figured I'd copy what was working.

Pro Stock John

iTrader: (34)

I think if you want to make 1000hp with a blower you will need to run cogs or a 12 rib setup. Personally I would source custom 12 rib pulleys over cogs, because cogs belts are very expensive.

There is a reason why folks say that you need to make 1 more lb of boost for every 1 pt drop in compression... If you say that the goal is 1000hp, and that 8:1 will make 3% less power at the same boost level as it would at 9:1, you need to make up 30hp.

I think a lot of folks can run 8.5:1 - 9.5:1 and it's all fine. At the higher compression levels you just need to use higher octane gas or meth since your IAT's and engine temps are higher.

Got Me SOM

iTrader: (2)

My compression is about 9.3:1 or 9:1 ish and it definitely doesn't feel as as strong as it did with 10:1 compression.

I personally think your compression is pretty damn low. Unless you are going to compensate by running a real big blower.

At 9 sec levels you are pretty much running C12-16 anyway.

kp

iTrader: (34)

Compression has taken a bad rap lately with all the pump gas BS, my old engine was 10:1 and I still ran in the 9s on 93 octane with no meth so if you know how to tune a car and dont do anything stupid its possible. That and knowing where your timing REALLY is and making sure the cam is in right of course.

Bottom line is compression makes heat, boost makes heat, if you can keep them under control then you are doing OK. If you cant you blow **** up no matter what the compression. There is nothing wrong with runing 8:1 compression but you are going to have to make up for it with more airflow, thats fine if you have the surplus and not fine if you dont

kp

iTrader: (34)

High IATs are not from compression, if anything they are hotter with less compression and more blower/turbo. Cylinder temp is another matter, but you would be amazed how just a little exaust gas getting in the chamber can cool things off so static compression, cam design, port flow etc all have to work together.

And I also disagree that you need a 12 rib or cog to make 1000hp with a blower, maybe you do with 8:1 compression and a huge cam. Arun is at 920 with an 8 rib and I bet he cracks 1K - and thats with the same belt that drives everything else. I am driving an F1A (which is bigger then your YSI) just fine with an 8rib and it will go much further. I doubt it will run an F1R at full speed but you never know..

ty_ty13

iTrader: (42)

so are you thinking an f1a is as big as a 8rib will run consistantly?

kp

iTrader: (34)

I dont like to speculate, I KNOW the SDCE 8 rib will run a F1A to 68K impeller with no issues. Other then that I have no idea What people tend to forget is how slow a car accelerates on a dyno compared to 1st gear at the track, thats when the belt will slip most. So just because it holds on the dyno doesnt mean it will hold making a pass in 1st, once they start slipping they tend not to stop the whole way down. Thats why logging boost is very important and its very easy to see belt slip in 1st gear.

onefastss223

iTrader: (14)

...I wish I had gone with an F1 blower instead of upgrading to the D1. At the time I upgraded to the D1 i was dead-set on fixing the 346. 2 weeks after I decided to go a different route. I'm going to be running 8.9:1 CR with the EPP FMIC & Alky Control so Im going to be way on the safe side. I built my car with alot of street driving in mind and also a possible turbo swap later on. However, if I swap anything I think it'll be for the F1 later on down the road. Also, I'm running the SDCE 8-rib and belt slip is more or less, non-existant. Then again, running a D1 to max impeller speed vs an F1-series blower at high impeller speed is incomparable I'd imagine.

No Juice

iTrader: (11)

Just run E85 and higher compression and call it a day

Pro Stock John

iTrader: (34)

Kevin, I am suggesting the 12 rib because while Arun is making great power, keeping belts on in street driving at big power levels is very problematic.... Sure an 8 rib can make 1000hp, the NMRA Renegade guys run 8.5's and faster with 8 rib belts.

ty_ty13

iTrader: (42)

this car makes very little street driving fyi.... just letting you know...

very interresting comments...

kp

iTrader: (34)

Driving normal on the street doesnt have anything to do with it, driving on the street with a belt cranked down like a guitar string sure does. Cool thing about a spring tensioner is when you let off, hit the limiter or shift the belt DOES slip and thats a good thing. As long as the belt doesnt get derailed it will stay on. But when you are running a cranked to the max belt and a good sized blower one pop of the rev limiter or high rpm throttle dump and the belt is out of there quite often.

You said you needed a 12 rib or cog to make 1000hp, and now it does not I wouldnt have any problems street driving mine at all. I can grab the belt and move it 3" with very little force which means almost zero wear and tear on the idlers and the belt itself.

You seem to be fixated on the belt thing, sure the F2+ and X trims arent going to work with an 8 rib, thats simple physics. But 1000hp is doable on a street car with a mid sized blower IMO.

ty_ty13

iTrader: (42)

i guess ill have to get the damn sdce tensioner sometime or another

kp

iTrader: (34)

Its not something you HAVE to get, but it does work pretty well. The ATI 8 rib can get you pretty far and I wouldnt replace it unless you are definately having slip issues. Most cars that throw belts are from alignment issues, vibration or usng long belts at high rpm, luckily the ATI 8 rib is a pretty short belt and they dont come off.