it i do do the thicker head gasket, is it really going to throw off cam timing? if so then i might just tell him to work around the compression. however, if he has trouble with the compression with the 3.0 pulley, i guess i will never be going to a smaller one and a boost pipe.
If when the motor is assembled he degrees the cams then he will adjust the cam timing to where they belong. Which should be done even if the stock head gaskets are used. Speaking of cams, what cams will the motor have. Also look at methanol / water injection.
showstopper what blower do you have? also what pulley are you useing? i hear that the smaller pulley you use on the blower the sooner or lower in the rpm ranch the boost will kick in.
i dont know if this is true. i hope so because i stepped down to a 3.0 pulley size. ill see how that does. i would really like not to feel sluggish in the around town driving as that is what everyone does most of.
that is one reason i chose a vt stroker block to go with this set up. it comes at 9:2.1 compression but my tuner says he dont feel comfortable with that compression and would like it a little lower so i could run higher boost.
he wants to go with thicker head gaskets to bring the compression down to 8:9 or something like that.
however, i dont want him dropping compression down to where the car feels sluggish and has no bottom end. i didnt pay extra for the stroker so he could suck away power!!!!!!
I have a P1-2 Procharger running a 3.4 pulley. up top it made 15-17lbs depending on air quality on the stock motor. we havent dynoed the forged combo yet but I assume it will be closer to 20lbs since I added a 10% overdriven Innovators West crank pulley. I figured this would be a better way to get more from the same pulley without losing belt wrap and adding belt slip into the mix. another way to get boost quicker is use 8 rib pullies with the smaller blower pulley so you eliminate the slip issues. If I see any belt dust I will know that its time for the complete 8 rib swap on my setup too...
compression for a 4.6 forged motor should stay in the 9:1-9.2:1 area for a blower combo.. these motors suffer down low as is so taking more compression out of a street motor would make it a DOG!
i have the intercooler already, should i need meth too? i thought that you only use both for super high boost levels, which im not going with. i have small blower cams in stage 2 ported heads that will be used. i also will be using the 8 rib pulley set up.
i dont want a dog on the street, i better see if he can tune it properly with the 9:2.1 compression. i dont see why he wouldnt unless for some reason he runs into problems with detonation. why though at only 12-15psi with that compression. i think i have all the nessary upgrades.
who are you having tune the car first off? hopefully someone reputable that has good experience with 4.6's. secondly yes you could use the meth with the IC as added insurance against detonation but if you have the adequate fuel system to support the power your looking at it shouldn't be a must to have.. I could use it on my combo too for more HP but I feel that the car will make 550+ without it on a safe tune so I am not going to use it at the moment.
basically what Im saying is overkill your fuel system if you haven't already.. mine is being completed in the next couple weeks with the new Fore Precision fuel hat, -8 line to the CPR rails and 75lb injectors. I also chose to run dual FPDM's to control all of this so I feel that my system will be way overkill for what the car will make right now.
A centrifugal car should be fine with 9.5:1. A twin screw or roots car is the ones that need 8.8 as they are in boost and generating a lot more heat down low. Don't go below 9.0 or your car will be a dog.
ok, screw it. im telling him that i want the compression left alone. with the compression 9:2.1 i should be able to run 15psi right?
if he cant manage tuning a car with this compression at the boost level and pulley size i want then i guess i will have to find another tuner right? should i take it he dont know what he is doing?
I was looking at alot of these blowers compressor maps vs what everyone is saying "the harder you spin em the better" and the such. Like they become more effecient the higher you spin the blowers. And thats just not the case.
lets look at a few maps from vortech here starting with the S trim.
Now as you can see, the circular areas are actually effeciency ranges (islands). And to the left on the map is the presure ratio and to the bottom we have Lb/MIN of air flow. Go HERE for a break down of what PSI a given pressure ratio is...look at the very top of the page. Goes from 0PSI (1.0 pressure ratio) to 25PSI (2.70 PR). Ok now look at the map and you can see that the most effecient island (72%) is gone at just over 9PSI. And by the time 13PSI rolls around, anything after that takes a noce dive in effency from 70 to 65. And remember that was a perfect world senario if your combo was setup perfect to macth the blowers islands. Look at the bottom of the map for LB/MIN...ROUGHLY every 10LB is 100HP. So you can plot you engines demands vs the boost your running and see where you end up on the map.
Ok now lets look at the S trim vs the T trim overlay.
Well for most guys running around on the street there will be no difference at low boost and the T trim will shine over the S trim at lvs above 13PSI to 18PSI. But atleast you have more of a shot at seeing the 72% island. Your just going to need to be able to make 500-600HP (flywheel) @ 10PSI and you will be there. But push more than 12PSI and you can forget about staying in tha 72% island.
And now onto the bad boy...YS trim.
Not really for a small inch motor IMO. You will need to make roughly 500HP @ 8PSI to get into that nice juicy 72% island and 560 to hit that 74% island and if you can do that, your trend should keep you going with the map and staying in the effency zones. But its all combo dependant.
SO my MAIN point is that the harder you spin a blower, the LESS effecient it becomes.
Second point is that blower selection isnt quite as important as turbo selection, but I hope this shows you that it IS still important, and really needs to be done if you want to make the most power with your combo. Most dont take the time to do this, and its why some guys make big power and some dont. Some of those big power guys get lucky, but others have planned it .
And since im on a roll, lets take a quick look at a turbo map. This one was the clearest of the T series. A T-66.
You can see a huge difference right away with the islands. 76% effency from 11PSI to about 35PSI. But these are HEAVILY combo dependant and if you get outside the center island the effency drops off FAST. Turbos must be selected to a specific power goal and engine demand, and this is clearly the case with this one. If you notice, to stay in the center island @ 15PSI your motor can only be taking in around 50LB/MIN of air...when you would actually be taking in somehwere around 60LB/MIN with the adverage modular(@ 6000RPM BTW....that demand goes down with RPM). This turbo would be a little on the weak side when pushed for our cars, but atleast as your boost came up it would pass straight through the center island. Probably right at your torque peak and then slowly slip out of its effency range as RPMs pass 5K. Thats desirable for a street car ofcourse (big midrange power) but wouldnt be ideal IMO. Would need to go a little bigger.