Oh SH** Monty...don't tell me that's in an F BODY!! Frank already flipped out when He saw John Meaneys(Sister combo to Franks current one 18* and similar intake) TT Vette. For an hour, He stated what a beast it would be,and He's scary enough to do it :D. HP is VERY addictive(like some of us don't know right?).
I know what you mean. The twin turbo thing has been in the back of my mind for awhile now. When I saw John Meaney's car in PHR, I started making the calls and arrangements the following monday. I ended up going with the same turbo's John used, just with a newer exhaust housing, same wastegates, etc. I'm hoping to get similar performance since the setups are practically identical other than the fact John's is a 400, and mine is a 427. As you know, both engine's share the 18* heads, but John used a modified cast intake with that custom sheetmetal box, while mine is all sheetmetal.
I learned form Rad Rides by Troy, who did the fabrication, that he's running relatively low boost, around 10-15 psi, and the cam is only in the 230 range. The cam is still the only part we haven't completely speced out yet. I should get the car back in 3-4 weeks, but I'm gonna make a trip down there this Friday, I hope, for some 'in progress' pictures.
I think you should convince Frank to go for it! Hopefully, he'll still let you drive it ;)!
Hey, I was wondering...with all those talks of turbos and blowers, I noticed that blower people recommend something like 8 psi...12 psi max. But then in the turbo threads like this one I see people saying they'll run 20 psi.....wouldn't that increase your CR to extreme values? (20:1 style) ??
That's true, but don't get too hung up on boost pressure. Boost ain't nothing more than stacked up air in the manifold. Who cares how much air you have in the manifold, all I care about is how much I can get into the cylinders. An engine with high-flow, efficient cylinder heads can make more power with less boost, than an engine with lesser heads with more boost. Take John Meaney's car for instance, he's running 18* heads and is making around 1200-1300 hp with less than 15 psi.
The centrifugal supercharger guys are limited by belt-slippage. You will see the higher-end supercharger setups going with cogged belts to minimaze this, and their boost levels will get higher. Alot of it also has to do with the efficiency of the power adder. As efficiency goes down, the power adder adds more heat to the intake air. Intake charge temperatures are a key factor in whether detonation is going to occur or not. This where the benefits of a properly designed and sized intercooler really come in. the turbo's do have a slight advantage in that they are more efficient, especially as the turbo gets larger. It may come as a surprise, but larger turbo's are more effiecient than smaller turbo's, and don't produce as much heat. Unfortunately, typically turbo lag increases, and their effective rpm range moves higher as the size of the turbo increases. It's all a trade-off.
Most turbo setups running 20+ psi of boost have been properly designed, not just engines that someone put a kit on, like alot of supercharger guys do. I'm not bashing superchargers at all, but when you install a kit on an engine that already has a pretty healthy CR, you are limited in the amount of boost you can achieve before detonation occurs. The turbo guys running 20psi+ have more than likely dropped their CR to 8.5 or less.
You also have to consider the octane of the fuel each is using before you make comparisons. There are alot of guys willing to run their own brew of fuel, or add 'off the shelf' octane boosters, or toluene/xylene to their pump gas to boost the octane.
Haaa good...for a moment there I thought there was some magic to turbo PSI compared to blower PSI. :lol: I have so much questions but I think I'll wait to get my book I ordered about supercharging/turbo.
I don't know for sure. But I attempted to calculate it based on "best guesses" and the information given in the PHR article.
The article states that he used 4.125" JE's with 35cc dish and a .300" crevice since the top ringe is that far down. They also said he went with a 3.75" stroke, for a classic SBC 400. Most 18* heads have a 70cc combustion chamber. The article also mentioned he used a copper gasket, most copper gaskets are either .039" or .040". The only other necessary info that is not mentioned is deck height.
Assuming a 9.025" deck and a 4.166" gasket and zero deck, I calculate his CR to be around 8.3. Assuming a .020" deck height the CR would be around 8.02. So I'm guessing somewhere in between.
I called Precision and told them that I wanted to replicate John's engine. They told me he used the PT-52's, which I have, and then I asked them for a recommended CR. They told me to stay between 8.0 and 8.5, so I'm targeting 8.3.
from experience with my little turbo buick I can share a few thoughts. The twin turbo setups can make plain stupid power with even pump gas. the big advantage with turbos is running efficient intercoolers and having "on the fly" adjustable boost. since the turbos don't take as much HP (just exhaust restriction) to turn like cent. blowers, they can really flow a ton of CFM when they spool up. the more modern turbos spool much better and are generally reliable provided you don't over speed them and keep good clean oil flowing through the bearings (only synthetic, turbos get HOT!!! especially when shut down after hard use). sizing the turbos, making SURE you have good control over the fuel (make sure you don't lean out, just like nitrous) and spark curve (less spark advance is needed on high boost) is really important as is managing all the heat the turbos create. problem with the vette is the engine compartment is tight already and adding turbos and keeping all the "luxury" AC and power steering can make packaging a problem. also, gettting enough radiator and cooling capacity is an issue. Monty, thanks very much for all your posts, some day, I will get a twin turbo vette. trying to find folks that could help me with a twin turbo ZR1 project. it will be high $$$ but hopefully will also survive some serious street miles and give me the performance I'm after. thanks for any advice as to competent builders that can assist. LPE says "no mas" :cool:
looking for advice on these guys to do a twin turbo ZR1. I will have the engine build by a LT5 specialist to lower the compression (368, 8 to 1 compr).
Turbo People (NY)
Fast Times Motorworks
Rad Rides by Troy
Kooks (for stainless headers)
any others??? I know this project will take some major bucks, and would be cheaper with a regular small block, but I really like the LT5 engine.
LPE, Callaway, and Mallet have all done twin turbo ZR1s but aren't building them any more. (and they START at 54K which is a bit steep).
any thoughts on who would be the best??? TIA for your help. :conehead
I use Fast Times Motorworks for all of my machine work and dyno testing. Since you listed them, you probably know they are one of the top engine shops in the country - and the fact that co-owner Chuck Samuels, and Nick Scavo are among the top turbo NMCA/NSCA/NMRA racers gives them a wealth of hands-on experience when building turbo and other high-end engines. However, they do not do the header fabrication and stuff. Give Jeff at Fast Times a call and he can build your engine for you and get the appropriate turbo's, wastegates, etc for you, you you'll need to take your car to someone to have the headers, intercooler, and exhaust fabricated.
It's pretty expensive to get the stuff fabricated, because it's a pretty laborious process of trial-fitting everything. The hours really add up and when they are charging you $50-$75 and hour, it really begins to add up. Materials add up to a substantial investment as well. An intercooler and all the stainless steel tubing can easily add up to $5000-$6000.
I really wish I was an accomplished welder. I seriously considered buying a nice Tig welder and giving a go at it myself. But I just felt that this was too big of a project to undertake as a learning experience.
Corvette Store
Check out this twin turbo Superram motor - cool.
