Guest bastaad525 Posted June 28, 2005 Share Posted June 28, 2005 A friend of mine stopped by my job tonite with a friend of his who wanted to see my Z. He was driving a '01 Lexus IS 300, L-tune version, supercharged with an intercooled vortech supercharger. He claimed 325hp to the rear wheels... pretty sweet, though I was let down to find he was running an auto trans. Just so you guys know, the L-tuned ones don't come with the supercharger, but are rather just a factory suspension and brake package and some body kit pieces. He added the supercharger on top of that. Anyways, surprisingly, he offered me to drive his car down the street and back... I was kinda reluctant, partially because I didn't want anything to happen, but mostly because I really didn't want to return the gesture but anyways he didn't even want to drive mine as he doesn't really drive stick... so that worked out. Well I was expecting to be blown away... but damn... well let me just say, weight is the true enemy of speed . Well that and the fact that this guys cam and supercharger didn't really kick in until like 4500rpm... so stomping on the petal from a stop produced anything but impressive results. At first I thought something was wrong and let off almost immediately but then he told me you have to stay on it so I went again. I mean, at 325rwhp I expected a nice big cloud of tire smoke from a dead stop. But then after 4500rpm it almost literally became another car, the exhaust note changed dramatically, I mean it friggin SCREAMED, and the car got a huge shove in the behind. It definately felt fast at that point and probably is the fastest car I've been in other than my own. I didn't really do much else than that, went around the block at a normal speed... the car felt very solid but not too stiff, probably a great handler with the L-tune package... argh but that automatic! Was a darn comfortable car though. So anyways after that the guy wanted to see what the Z could do... my friend been doing some bragging on my behalf he's a soon to be convert looking for an early Z to turbo himself. Anyways, we raced twice and both times I jumped out 2-3 cars on him right off the line... that's what 300ftlbs at 3000rpm will do baby! Actually even this surprised me as I am really bad at launching my car well (proven by that Gtech giving me 2.7 sec 60' times!). It seemed that once his car got going we were pretty evenly matched though... not bad considering he's got nearly 100hp to the wheels over me! We took it up to like 80mph (a very long section of street with no intersections, in an industrial area which is all but abandoned at night when I'm working) both times and it didn't look like either one of us was pulling on the other. After the two runs he asked for a ride and I gladly obliged He said I must be way off on my dyno numbers as the car definatley felt like it had more than 230-240rwhp. He was feeling that 300 ft lb kick in the chest pretty nicely , but I told him that mine is the opposite of his, making great down low power but falling off really quickly, unlike his which likes to scream all the way to redline. He didn't seem to really 'get' the relationship between torque and hp. I also explained that his car weighs like 1000lbs more than mine. He didn't seem to technical minded at all, really, and couldn't answer a lot of the questions I had about his car. That fact and his age (mid 20's) tells me his car was probably paid for by mommy and daddy but I have to say the guy had a much better attitude than a few of the other guys I've met with nice cars that were bought for them. He was a really cool guy and really showed that he liked the Z a lot, though his smile faltered a bit when I told him how my car cost well under $10k It was a really nice car though and a daily driver. I'm not super fond of the IS 300 but it is the last real inheritor of the Supra Legacy, running that same 3.0 liter inline 6, it was hard not to like it. I guess this is the last year for that engine at all? The new IS's will run a V6 according to Motortrend. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted June 28, 2005 Share Posted June 28, 2005 People just don't get it...... I had a ricer friend of mine tell me I must have been pushing 500rwhp because it threw him back more than anything he'd ever been in. I told him that was the torque that he was feeling and that I'm probably "only" pushing 400hp to the wheels. All he knows is peak hp and unless my car really changed his way of thinking that much that's all he'll ever know. He also said, "you're running 13's easy". That was when the conversation ended..... Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 28, 2005 Share Posted June 28, 2005 Let me guess....his super charger is a centrifugal unit. No other explanation for why his boost comes on so late. Sounds fun, I sure like how the turbos spool so quickly -- 400 ft-lbs is a lot of fun down low. Quote Link to comment Share on other sites More sharing options...
Guest Battle Pope Posted June 28, 2005 Share Posted June 28, 2005 Yes, they are changing to a 3.3 liter V6 and changing the moniker to IS 330. Quote Link to comment Share on other sites More sharing options...
b__sosick Posted June 28, 2005 Share Posted June 28, 2005 nice! I love those cars. Luxury lexus styling with plenty of speed. :] Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 29, 2005 Share Posted June 29, 2005 yeah centrifugal, the one that looks like half a turbo. Why does that mean his boost hits so late? I thought the advantage of ALL superchargers vs. turbo's is that boost response on the SC is instant and it's much more responsive? That's why I was so surprised when I drove his car, I expected it to just feel like a really strong motor, no noticeable boost onset at all, not be twice as laggy as mine is! Quote Link to comment Share on other sites More sharing options...
Guest Battle Pope Posted June 29, 2005 Share Posted June 29, 2005 It has something to do with a design deficiency when compared to a roots or twin-screw blower. As you know, superchargers spin the turbine in relation to engine RPM. However you also need to consider the centrifugal supercharger doesn't move a fixed amount of air, whereas the roots and twin-screw do. Plus, due to the turbine-like design, it is much like a turbo in the sense that it requires much higher RPM to produce boost. Here's a nice article about the different s/c styles. http://www.superchargersonline.com/content.asp?ID=76 Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 29, 2005 Share Posted June 29, 2005 well then why the heck would anyone go with one of those? It doesn't seem to have any of the advantages of a turbo OR twin screw SC. Quote Link to comment Share on other sites More sharing options...
Guest Battle Pope Posted June 29, 2005 Share Posted June 29, 2005 1: price. a vortech centrifugal system for a SBF can be had for a mere 1500 bucks on a good day. 2: Create less heat than any other setup. 3: simplicity. Extremely easy to set up. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 29, 2005 Share Posted June 29, 2005 I thought the other kind of SC, the one that just bolts straight to the manifold, were also usually cheap and easy to install? Quote Link to comment Share on other sites More sharing options...
Guest Battle Pope Posted June 29, 2005 Share Posted June 29, 2005 They're also easy to install, yes, but they're also much more expensive from what I've seen. Quote Link to comment Share on other sites More sharing options...
Phantom Posted June 29, 2005 Share Posted June 29, 2005 A properly set-up centrifugal should come on down around 2200 rpm, not 4500. Somethings not right with his installation. Go to the ATI Procharger website and look at some of the torque/HP curves they have for various engines and they all indicate lots of extra umph at lower rpm's. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 29, 2005 Share Posted June 29, 2005 Problem with centrifugal is you've got to design the install to make full boost at redline since it's directly geared to the crank. The airflow from the unit is proportional to the square root of the RPM, so you get only 25% of the airflow at half the redline RPM. This results in only a fraction of the boost until you get the engine wound up, and the effect is more pronounced on a high revving engine. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 3, 2005 Share Posted July 3, 2005 Problem with centrifugal is you've got to design the install to make full boost at redline since it's directly geared to the crank. The airflow from the unit is proportional to the square root of the RPM, so you get only 25% of the airflow at half the redline RPM. This results in only a fraction of the boost until you get the engine wound up, and the effect is more pronounced on a high revving engine. That makes more sense. Still seems a stupid way to go vs. a turbo but hey what do I know I think it really had to do with his cam too... again he didn't really seem to KNOW exactly what he had in there, but he said it was a 'big' cam. It's kinda sad when guys go in not knowing much about performance and specify these certain parts for a build and then end up with something way off base from what they probably would have wanted. Having an automatic trannied, heavy car, that only makes it's power very high in the rev range, doesn't seem like much fun to me, and the thing sure made a racket when the cam and SC 'came on'. He was saying how he was getting harrassed by cops all the time... well with so little oomph down low I can see why he'd be so tempted to wind it up all the time. Quote Link to comment Share on other sites More sharing options...
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