The problem is your logic is still flawed. 1PSI is still 1PSI, that is what I said. I also have an intake manifold gasket leak which is causing a drop in pressure, not just the extra cubes I have gained. I may have more cubes in my combo but my compression has also been dropped to 8.5:1, well below a stock levels. The extra cubes effectively have to make up for that drop in compression to bring it to a comparable power level to stock.
Man......you're really out to lunch. You've gone from missinformed poster, to strait up
artist. You're now twisting your logic to fit your arguement. I tried to be nice before, it's clear one of of those people that can't admit he wrong no matter how many times his arguement has been defeated!
I'll say it again.....so pay attention this time. Boost means ****!!! Nor is it a direct indication of horsepower. My little M90 will make 12-13psi.....does that mean it's making more power than your Kenne Bell because you're only seeing 10psi?!?! Of course not! You have full exhaust and intake mods, you have blower cams and you have increased engine displacement. All of these factor work in your favor to remove restriction with your engine and increase it's flow capability.
You now complain about this mysterious intake manifold leak that's the cause of your pressure drop?!?! Let me tell you something.....any manifold leak that's causing you to lose what would otherwise amount to a solid 4lbs of boost in any other 4.6L application (since that's what you're particular pulleys size registers on any other 4.6L mustang) would be doing a lot more than just showing up as a pressure loss on your gauge. You state that the car starts, runs, idles and drives like a champ. Right there that tells me this mysterious manifold leak can't be all that significant (if in fact one exists at all). I swear, your like that kid on the block who always needs to have a "one up" stories about what his dad does for a living so the other kids will continue to like him.
Your lower 8.5:1 compression ratio has nothing to do with the amount of boost you’re combination will make as it does the amount of cylinder pressure you’re able to safely run. Sure, under vacuum, you’re going to loose a little bit of initial torque, but once under the influence of positive manifold pressure, that decrease in compression allows you to run more timing and less fuel as cylinder pressures increases. By adding increased displacement you’re now seeing a boost pressure drop across the board. You’re no longer filling 281ci of cylinder volume with each intake stroke, you’re now having to fill 300+ci. Since you haven’t increased blower speeds to account for the additional volume your engine is now displacing, it along with your higher flowing intake and exhaust components are causing a boost pressure drop across the board. You’re problem is, is that you confuse boost with airflow...it is CFM that makes the torque and power, not pressure alone. Although boost has dropped, your CFM has increase, thus increasing your engine efficiency and as a result increasing your horsepower and torque making ability.
A centri blower would have to overcome that low end compression loss in order to even keep up with my KB. That's why centri blowers don't need forged internals the same as positive displacement blowers, another popular internet myth. They don't see the violent torque shock as a PD unit gives out. In fact most centri blowers will never need an internal change unless you start pump high PSI volumes through them where detonation becomes an issue, which never happens cause the BELTS KEEP SLIPPING! Even with an 8 rib pulley set up centri blowers throw belts commonly. Do a search for "do my dyno numbers seem low" and you will find every Centri thread ever made. I have never heard of any complaints from any KB owners on here. Post a thread about that.
I’m not sure who’s been feeding you your information, but they’ve really filled your head with a lot of the wrong stuff.
Yes, under N/A conditions, horsepower and torque levels will suffer to some extent with a drop in compression. Although not ideal under naturally aspirated going from a 9.0:1 to an 8.5:1 compression ratio isn’t going to turn a 4.6L V8 into a total slug under vacuum conditions either. You need an example of this….compare a ’99-up 4.6L SOHC PI engine, to an earlier 4.6L SOHC with a PI head swap. The compression ratio of the stock PI engine ranges in the 9.0-9.2:1 range. The head swapped car ranges in the 10.2-10.4:1 range. That’s a fair jump in compression (much larger than the previous example), yet the horsepower difference between the two engines is only about 5-10hp and like amounts of torque at the flywheel.
Running the two cars head to head doesn’t provide enough of a difference to give one car any distinct advantage of the other either way.
You’re half right in your logic, that since a Positive Displacement blower has the ability to move such a large amount of air at such low blower and engine RPM, it quickly pressurizes the engine and the “race is on” so to speak. But from this point on, the remainder of your argument takes a dump. Before this goes any further, let me illustrate one point again. ALL SUPERCHARGERS CREATE HEAT!!! Anytime you pressurize air, its temperature increases. It’s not magic, it’s thermal dynamics. It is true, that Centrifugal superchargers don’t make as much heat as Positive Displacement superchargers do by comparison, but that’s not to say they don’t make any at all. Like any power adder, the harder you push it, the more heat it makes and to say Centrifugally blown cars needing forged internals is nothing more than an “internet myth” just shows how green on the subject of power adders you really are. I mean….turbo’s make less discharge heat than any supercharger moving the same volume of air. Are all those builders just wasting time and money by running intercoolers and alcohol injection for those set ups as well?
This brings us back to the argument that “boost isn’t just boost”. Since a Centrifugally blown engine is make that much less discharge heat than a twin screw at similar airflow levels, it allows the tuner to add timing, pull fuel and get more aggressive with the A/F ratio accordingly. If you thought that drop in compression worked well in the Twin Screws favor, wait till you see what it does for the Centrifugal car. I mean….the Centrifugals power band may be narrower than the Twin Screws, but if you thought the power came on hard with them before, you ain’t seen nothing yet!
The bottom line…..dropping the compression ratio works in the Centrifugally blown set up every bit as well as it does for a Positive Displacement blown set up.
And you’ve again strayed from the point. We’re illustrating the reason
your car is able to make so much power while only seeing 10psi on the gauge. Not recapping the history of superchargers and different combinations over the last 30-years.
Again…..you’re additional modifications are the reason you’re able to make as much power as you do, at lower boost levels compared to other stock vehicles. It’s not because you’re 1.7L is a superior supercharger to the S or T-Trim
Vortech…..because again, I’m sorry to burst your bubble, but it’s not! In case this isn’t clear enough for you, let me say it again……The S-Trim and T-Trim will support more horsepower and torque than a 1.7L Autorotor will…..PERIOD!!!
As far as the belt slipping comment…..I’m quite sure I’ve already address that, but I’ll say it again. Under modest power levels and pulley diameters, belt slip with a Paxton Novi or
Vortech S-series blower is non-existent….never mind “throwing a belt”. The only issues that have ever seen make it to the surface is when someone insists on trying to used the stock belt when swapping out an excessively small diameter blower pulley instead of spending the $45.00 on a proper length belt, or around weak blower brackets sometimes associated with Procharger systems. Again….belt slip can be cured by upgrading the pulleys system and the problem can be just as common with Positive Displacement superchargers as it is with Centrifugals. As a matter of fact, if you want to continue to touch on the issue, I’ve heard more than a few people complain about slipping belts when trying to run a 14psi pulley on their Kenne Bell.
coincidence….maybe……but more likely wishful thinking that the stock 6-rib pulley is up to the task. Either way….that was a design flaw on Fords part, not the part of the Supercharger manufacturer.
Hell….even Thunderbird Super coupes utilize an 8-rip pulley system and they’re only spinning a little M90 by comparison.
sorry dude your wrong on that one, he was in the nines with the 2.2L huffer 9.67 to be exact, read first post by jim here -------->
http://forums.stangnet.com/showthread.php?t=672213
My mistake.
I wasn’t aware he broked into the 9’s with the 2.2L
That’s still not to say that Centrifugally blown cars aren’t capable of the same feats. Just because there are no mod motor guys running 9-second cetrifucal cars that post here (that I know of) doesn’t mean there aren’t any, anywhere. I could easily link you to half a dozen cars that are running 8’s with Centrifugal blowers and 10.5” tires…..but that doesn’t mean it couldn’t also be accomplished with a Twin Screw, were the blower sized accordingly.
and even the small KBs are pretty impressive at the track, check these vids out of a 2.1@9psi running a high eleven no
suspension upgrades just
BBk CAI,flowmasters and drag radials.
http://videos.streetfire.net/search/kenne+bell+gt/0/c14abea0-8b30-4e2a-ba12-988500f265f8.htm
I don’t recall ever stating otherwise. I’m quite aware that 11’s are very possible with the smaller Kenne Bells. Hell….There are one, or two guys running 11’s in full weight Thunderbirds with lesser (Eaton M90) blowers. My argument was based around Tweeked GT’s statement that he could handle
any S or T-Trim based blower at the track. He’s so consumed with boost figures that he doesn’t realize they only tell half the story. He can’t see that by increasing the efficiency of his engine, he’s increased it’s capability to utilize the incoming airflow. Just because he’s only seeing 10psi on his boost gauge, doesn’t mean the blower itself is producing any less air than the guy running the stock displacement, no bolt on engine seeing 14psi. Both the S-Trim and especially a T-Trim Vortech will support more horsepower and torque than a 1.7L Kenne Bell and the same principals apply for increasing the engines efficiency. Just because he hasn’t run a comparably modified Centrifugally blown car at the track yet, doesn’t mean they aren’t out there. He has after all only had his car running for a few months….half of which have been snow filled.
Gearbanger,sorry for "yelling" on my earlier post but i just dont like the fact that you supposedly know so much about KB blowers and you dont even own one. I dont assure anything about centris because i DONT OWN ONE and no matter how much i've read on them it doesnt make me an expert on something i havent had hands on experience on.
So what is it that doesn’t sit well with you. The fact that I know what I’m talking about, or that fact I don’t own the product? Just because a person doesn’t own something, doesn’t mean they aren’t able to have an opinion and a good working knowledge of their design and capabilities. I mean….I don’t own a restaurant either, but I can certainly grill up a mean T-Bone!
You better than anyone should know ownership of a particular item in no way gauges their expertise on the matter. Anyone with a credit card can own a blower, or a fast car for that matter, but it doesn’t mean they’ve got the first clue as to how it works. Tweeked continues to prove that theory with every post! I’ll admit, I drop the ball on occasion my self, but when have you not known me to admit I my folly when proven wrong? More often than not, I won’t voice my opinion on a subject unless I know I’m right. Especially when the end result of what I’m saying has a bearing on how a person spends their hard earned money.
I’ve done enough research, read enough statistics, have worked on and been around enough N/A and power adder combinations to have a pretty credible working knowledge of the subject. I grew up with a mechanical background, in a predominantly Ford based environment. My Father has been a well respected mechanic for over 50-years and a couple of my brothers have gone the same route. To say it’s in my blood would be a vast understatement. I’ve always been a person who does his own work and research for as long as I can remember. As long as it was within my capability, I undertook the task on my own. If it was beyond my knowledge or abilities, I did the research that was necessary in order to make it happen or swallowing my pride and asked for help to complete the task so that I would be able to do in on my own in the future. I don’t at all claim to be an expert with regards to any power adder, but I’m no novice and this isn’t my first barbeque either. I’m certainly able to respect another person’s opinion, but it doesn’t mean I shouldn’t speak up and voice my own if I feel differently about it. Just as you’re have no trouble doing right now.
