skalor Posted May 20, 2005 Report Share Posted May 20, 2005 Since, I'm keeping the TGP I decided that I'm going to throw some money at it this summer. I've been looking at cams a lot lately and which off the shelf cam would make the best turbo cam. Since we have a lot of exhaust backpressure we probably want a cam that has very little to no overlap. So here are the general specs of the cam I started looking for: -little to no overlap -at least .420 lift -as much duration as possible to satisfy the above two I found a nice excel spreadsheet on s-series.org and I checked out a couple specs and they look accurate. Here's the link: http://www.s-series.org/htm/tech/60DegreeCams/60DegreeCams.zip Anyways, according to to a couple sites I've seen about computing valve overlap...All you have to do is add up Intake opening and exhaust closing values. So far the best cam that fits my requirements is the Crane Powermax H-272-2, which only has 2* of valve overlap. I really liked the H-260-2, but is has 14* of overlap. :shock: There are a couple others on there that have less than 10* of overlap, but the H-272-2 looks the best to me because it's the craziest with the least overlap. Does have know the stock cam specs?? I'd like to see what kind of overlap the stock cam has. 8) Quote Link to comment Share on other sites More sharing options...
Intlcutlass Posted May 20, 2005 Report Share Posted May 20, 2005 The never ending debate I had found (from reading), that because these came with a stock cam, probably the best thing to do is replace the rocker arms from a 1.52 ratio to 1.60 tario. That would give you the same amount of lift through each lobe..... I was looking into the Crane cams, and Jeff M had stated that messes with the computer too much. I decided (For me) that it just wasn't worth the added cost and potential headache if I put a cam in that hurt the engine performance rather than help it.... Just my opinion only..... Thats when I found this: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7972898638&ssPageName=STRK:MEWN:IT Quote Link to comment Share on other sites More sharing options...
J Posted May 20, 2005 Report Share Posted May 20, 2005 The never ending debate I had found (from reading), that because these came with a stock cam, probably the best thing to do is replace the rocker arms from a 1.52 ratio to 1.60 tario. That would give you the same amount of lift through each lobe..... I was looking into the Crane cams, and Jeff M had stated that messes with the computer too much. I decided (For me) that it just wasn't worth the added cost and potential headache if I put a cam in that hurt the engine performance rather than help it.... Just my opinion only..... Thats when I found this: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7972898638&ssPageName=STRK:MEWN:IT i just bought the same cam, same price Quote Link to comment Share on other sites More sharing options...
skalor Posted May 20, 2005 Author Report Share Posted May 20, 2005 I'm not too worried about the computer as I'm already setup for reprogramming eproms. Of course the computer is going to need to be reprogrammed as we have a speed density based computer and changing cams completely alters the VE tables. To anyone responding, please only post factual information as I don't think we need a nother topic about someone else's words of wisdom. This thread is for people that can actually think on their own without being told what to do. No Flame intended Intlculass. Quote Link to comment Share on other sites More sharing options...
Intlcutlass Posted May 20, 2005 Report Share Posted May 20, 2005 This thread is for people that can actually think on their own without being told what to do. No Flame intended Intlculass. Jeez dude wheres the love? :kiss: Quote Link to comment Share on other sites More sharing options...
skalor Posted May 20, 2005 Author Report Share Posted May 20, 2005 I didn't mean to say that you can't think on your own. I meant that I want this thread to be more than "what cam should I get?". I don't think we need another ones of those threads. I just thought it would be nice to actually post specs and actually figure out what off the the shelf cam would be the best choice. Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted May 21, 2005 Report Share Posted May 21, 2005 YOu know that changing the rocker ratio also alters the overlap in a way. How...the valve opens more at that same degree of overlap. Would you notice..not really. So 1.6 rockers on the exhaust won't hurt. Also..the 270 doesn't have 3° of overlap..but according to your timming at .05 lift it has 2° of overlap..and the 260 crane has -4°. Look at the timming at .004 for both the 260 and the 270...WOW. But you also know that you cain't use the 270 to its full potentual without some exhaust port work or the 260 for that matter. I've notice that the only good cams out of the shelf are the Crane 260 and the Compcams 260. The crane Compucams... . NO. I also found Engle cams has some good "turbo" cams. I just don't know about them taking away at the exhuast timming..beeing a exhaust choked engine and all..but oh well...care to try. http://207.178.130.99/catalog/old_catalog.php Theres no definate awswer to cams. Turbo Ford guys have been at it for dacades..and still...no definate awswer. Depends on what you want...top end..low end...turbo upgrades..ect. But for STOCK. I'ts highly recomened you get the 260 cams. sorry if its still not the info you need. Its too broad. What are your plans as far as upgrades...turbo?, head work?, trans work?, drag race?, auto-x? ,just milder?. Quote Link to comment Share on other sites More sharing options...
RareGMFan Posted May 21, 2005 Report Share Posted May 21, 2005 What kind of improvements/numbers can one expect to see from a Crane or Compcam 260 over the stock TGP cam? Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted May 21, 2005 Report Share Posted May 21, 2005 The 272 is too aggressive for stock heads/intakes, and definately for the stock or Jeff M chip. With the 260 (actually the GM version of the 260) in my STE (along with 3100 topend) it still sounds like the stock cam, and it kept all its lowend torque but gained massive midrange and topend power. It pulls hard all the way to the limiter, shift points could probably be raised another couple hundred RPM's, and limiter 4-500rpms, and keep in mind this is with the T25, with something a little bigger like a GT28RS or a GT2871R it would be insane. From what I have been able to find about the stock cam, it appears to match the one in column S, or number 18 on that excel sheet. This summer I'll be putting a Crane 260 in the Lumina with 1.6 intake rockers and 1.5 exhaust. With stock heads I don't feel that the added lift with the 1.6 rockers on the exhaust will be beneficial. As far as off the shelf cams go, I really feel that the 260 is one of the best we can get. I'll try to get before and after dyno results with stock w/1.6 rockers vs. crane 260 w/1.6 intake, 1.5 exhaust rockers and see what the difference is. This will be with no other changes as I will be keeping the Gen II topend and won't be making any chip changes or anything. Shawn Quote Link to comment Share on other sites More sharing options...
skalor Posted May 21, 2005 Author Report Share Posted May 21, 2005 TurboGTU, I plan on upgrading the turbo, but I don't know when that's going to happen this year. I already did do some work to my turbine housing to help improve flow. I bored out around the turbine wheel roughly .060 and it hasn't hampered spooling at all. I actually think that it improved topend flow, but I never tested the backpressure before boring out the housing so I can't really prove it. I've been reading about turbo cam design from the turbo ford guys so it's funny that you mention them. From what I've been reading is that you want the exhaust valve to open until after BDC. The reason for this is that if the exhaust manifold has 30 psi of pressure then you don't want the vavle to open until a crossover is reached. Otherwise you'll actually be pulling in from the manifold before pushing it out. I guess I'll have to add another spec to the list I'm trying to get matched up decently. Obviously I won't find an off the shelf cam that's fits that exact description so I'm going to try and minimize it so that is opens as close to BDC as possible. I looked an the Engle turbo cam and I wish they had more specs for valve timing. I'll have to send them an email to see if they'll send me some more info. Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted May 22, 2005 Report Share Posted May 22, 2005 You know what...even the Crane 192 is an improvement over stock. I'll shoot myself on the foot for the Comp cam. But I stand firm on the Crane 260. THe reason I got the Crane 260 is because I knew dam well I was going to port the heads and manafolds..and add a turbo upgrade down the road. I had mached the Cam to my "theratical" head flow. I wanted lots of mid and upper..so that was my pick. So stock for stock...Crane 192 and 260. The 192 would be perfect..since it almost mathches the stock GM cams but more lift and duration and still has that lovable overlap and timming events. NOt the GM HO cam..that seems too retarted for turbo. (theres like 6 more gm cams missing there). If your not going to touch your heads(doen't sound like it)...the 192 or 260 if your greedy. Actually...list all the cams that have neg values for intake openning BTDC and exhaust closing ATDC. That will leave you the ones with the least overlap. But before you go buy a cam...try the old 3100 1.6 ratio rocker arm on the exhaust valves..and go for a spin..and check the difference. Put those on the intake too and repost..won't hurt to try...just $15 j/y rockers, sealant and a free day. With the Crane 260...I woun't know..I have ported the heads and everything..but some people report that they get like 15 peak hp more N/A. WOuld be nice to have a before and after dyno though..see if the power flattens out more through out. Still not what your looking for eh Quote Link to comment Share on other sites More sharing options...
skalor Posted May 23, 2005 Author Report Share Posted May 23, 2005 I might just try out the 1.6 rockers for now as I'm taking the upper off for changing my injectors and the new vacuum line kit from GM. What years are the 1.6 rockers?? Are they the stamped or roller?? Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted May 24, 2005 Report Share Posted May 24, 2005 They are the 94-95 non roller. I got mine from a 95 beretta since I don't have to remove the dogbone or anything like the w-body (got them yesterday). Intresting thing thoug...as I was looking for my old rockers...and found some old sbc and 87 sbc self alighn rockers...they appear to fit this motor. The 95 rocker have the pushrod hole a little closer to the center though...thats the only difference. But back to my findings...If this is so...I would think cheap aftermaket stamped steel high ratio rockers for sbc would work also. :!: :?: Quote Link to comment Share on other sites More sharing options...
skalor Posted May 24, 2005 Author Report Share Posted May 24, 2005 I actually have a set of '94 3100 heads sitting in my garage with rockers on so I'll have to check them out. Can I use the later roller 1.6s or are there interference issues?? Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted May 25, 2005 Report Share Posted May 25, 2005 The later 1.6 rollers have a mount on them with a notch in it that fits into the notches on the newer heads, so you would have to either notch your heads or modify that mounting plate so it would bolt to your heads. I would go with the rockers you have sitting around for now. Shawn Quote Link to comment Share on other sites More sharing options...
Jeff M Posted May 27, 2005 Report Share Posted May 27, 2005 The best way I know of to find what you need in knowledge on a new subject/project, and if it’s a pretty complex issue, is to look at the experts! One I would recommend is David Vizard (sure you heard of him but anyways), he has published tons of papers and books, runs many seminars and all his info is golden, many who I know that are very smart in the field all agree this man knows his shit!! So do a search on his papers and books for a cam topic, also a turbo one as he can cover each in those topics, you kind of have to compile from him to get all the goods. Then there are other places, SAE has a vast library or published papers, even some pretty heady books on engines and many other topics (I have a collection as well, even one on the 60 degree ). There is this site: http://dansayre.com/ti/ti_catalog.htm And it has a cam seminar that would be valuable to have. I have the seminar with Ken Sperry; manager for power development/gasoline engines at General Motors, & Pat Baer; Dodge Motorsports and it will take a few days to get through it but some vast info and awesome surprises covered by some of the leading men in air flow development. It’s kind of hard to find the link to their catalog so here it is, you can scan it for yourself: http://dansayre.com/ti/pdf_docs/TI_Catalog_by_Subject.pdf There was another web side I found once that was chocked full of this level of info for the needs of engine designers (cam, intakes etc) but my Favorites are in the thousands and tough to look through even though they are categorized, but search engines will find them and even more new info available for your cam project here. Jeff M Quote Link to comment Share on other sites More sharing options...
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