Pyro

Yes, that sounds like a TPI engine. If I remember correctly, those made 245 hp in 350 cid and 230hp in 305 cid and a ton of low rpm torque. Be careful, that TPI could be a 305. The TPI engines make great torque and get good mileage but not good for rpms. They do make aftermarket intakes that fix the TPI low hp problem. If you want a low rpm torque monster and a quiet daily driver then a TPI would not be a bad idea. But getting the injection to work in your car would be much harder than installing carb linkage. LOL. I would install the 78' with a 268 Comp Cam using the 350 trans and a 2200 to 2500 stall torque converter. 240's have 3.36 gears which should help keep the rpms down a little lower. But they will still be a little high for most peoples taste. I personally didn't like an automatic transmission in my V8 Z. And I had a lot of problems with the 700R OD transmissions. To make it really nice, install a GM T5 5 spd trans, 3.90 gear, blocker hugger headers, single 3" exhaust, vortec heads, and a 292 comp cam. This would make a low 12 second Z! I had this combo a few year ago and wished I would have left it that way. Since then, I made it faster but started breaking things. Not as fun that way.......

There is nothing magical about 327 corvette engines. A 350 with the same stuff on it will kick a 327's butt. The same goes for a 383 over a 350 or a 327 over a 302 or 283. Cubic inches rule. What makes an engine run is all in the heads, cam, intake and exhaust. The block only needs to stay together. Plus heads have improved greatly over the past few years. Those old 327 heads suck compared to the new vortec heads or any other after market head ( AFR, dart, trick flow, ect.) The easiest way to make 350 hp is to buy a crate engine. You could even buy a new Goodwrench 350 for 1200.00 and install a cam/springs, intake, carb, and headers and make 350 hp. Then later install a better set of heads and make 400 hp. Go to chevyhiperformance.com. They did a nice 7 or 8 part build up of this same engine which you can read from their web site. Or buy a set of 64cc vortec heads and install them in a 350 with flat top pistons and a 280 comp cam and make 380 to 400 hp. The 350 doesn't need to be anything special. Cast crank, cast pistons, and two bolts will handle a bunch of power (500+). A junk yard 350 short block with a good quality rebuild by a "real racing machine shop" will make a big difference. (bored with torque plates and balanced) Block hugger headers into a single 3" exhaust system works well on a V8 Z. Don't make a big, heavy, noisy, and expensive exhaust system if you are going to make under 400 hp. Gm T5 5 spds are hard to find. Make sure to get the 5 spd from a V8 if you are going to use this transmission. They will handle a lot of power if driven correctly, that is, be easy on the clutch drops and shift kind of slow. I hate 700R transmissions. Expensive, don't shift when you want, short lived, and feel wrong in a Z. But that is just my opinion after using a few in my Z. I now use a T5 a love it. It runs 10's and lives because I shift her like a school bus. It might be a good idea to look for a complete engine and trans set up to drop into you car. Or you could sell your car and add it to the 4000.00 budget and buy a Z with a V8 already in it!!! Which is really the easiest way to get 350 hp in a Z.

It's getting deep in here!

A turbo shop can machine your old stage I housing into a stage III housing in order to fit in the stage III turbine wheel.

I feel the stock manifold is not all bad. It is almost a header compared to some manifolds I have seen. You could try using more exhaust duration to make up for the lack of a header. A 280/290 cam would help out exhaust flow a bunch. Plus a good 2.5 or 2.75" exhaust pipe and high flow muffler would help. I have seen V8 engine dyno runs using split duration cams produce the same max hp and torque with or without headers. However, mid range torque was be reduced by 10%. Why use a N42 head then a 2mm head gasket? I think it would be better to use a stock gasket (1mm felpro) and a P79 or P90 head. Much better head design in the P series as compared to the N series.

A turbo blanket and exhaust insolation wrapped on down pipe would help reduce heat. But seems to me there would be a cooler place to mount that box.

I have seen an old chevy 292 inline 6 turbo charged. It was a car that appeared in a Hot rod mag 3 or 4 years ago. A 1938 ford or something like that. The car was a street car but was running in the 9's in the 1/4 mile. I think he was running over 20 lbs of boost into a Holley carb! He used a power-glide for a tranny. I bet the ford 300 inline 6 could do the same. Or even better, pontiac made a overhead cammed 6 in the late 60's for the firebirds. I think it was around 250 cid.

Yes, 114 mph is getting there! And the cam you used was pretty mild. So, I think that combo worked pretty well. When you changed to the bigger cam and single plane intake is when you had the problems. Maybe the valve springs aren't strong enough or the fuel pump isn't keeping up? Or a different tune on the carb could help? You should pick up only 1 or 2 mph with a 4.11 gear swap. Most of the improvement with the gear swap will be in the et. Maybe as much as 0.5 seconds. I noticed you are using 190 cc afr heads in your label. Those are the best heads out there! With a set-up like that, your car should be runing 118 to 120 in the 1/4 mile. In any case, I would use the performer rpm intake. In this month issue of hot rod mag. they tested 6 manifolds and the performer rpm airgap made more power than all the others tested. What are you using for exhaust?

Your 1/4 mile et looks pretty good with the mph. However, your MPH seems low for a 383 with a pretty big cam When I first did my V8 swap I ran 12.8's at 110. It was a 350, 11:1 cr, 292H comp cam w/roller rockers, GM T5 trans, r200 w/3.90 gear, holley 750 vac, performer rpm intake, block huggers, 2.5 inch single exhaust, and 165cc GM "fuelie, double hump" heads with 64cc combustion chambers and 2.02/1.6 valves. Later, I installed 200cc iron eagle heads with 64cc chambers, full length hooker headers, and dual exhaust and picked up 10 mph and dropped a full second (11.8's at 120). Then installed a set of MT drag slicks (26x8.5x15) and a 175 shot of N20 and ran 10.7's at 135 mph in the 1/4 mile and 6.9@110 in the 1/8 mile. 135 mph was at the very top of 4th gear! I made all these gains using the same engine, cam, intake, carb, diff, and trans. So what i'm trying to say is....... You didn't mention what heads and what kind of exhaust you are using but I bet you need to make improvments in the head and in the exhaust area. If you already have good heads and exhaust then you have a problem somewhere else because your not making enough MPH. FYI, the Performer RPM airgap (dual plane) intake kicks butt and works great on just about every application.

Hmmmmm........ Yes swicthing to the 0.63 exhaust turbine housing will slow boost a little but not that much. Maybe 200 or 300 rpm difference. The .48 will spool up quicker but will not flow enough for the t4 compressor. Who built your turbo? Is there a chance they clipped the exhaust turbine wheels to improve flow? Radical clipping of the exhaust turbine wheel will really slow down spooling. I'm not 100% sure but the 57 trim on the intake compressor could be the problem. I remember reading that a 57 is too big for a L28. I'm sure a turbo "expert" could offer more information. Maybe you should post another question aimed at compressor trim sizing and boost responce. I'm surprised you didn't get more replies to this post. Try manually locking your wastegate closed and see if boost comes on sooner. But be carefull not to over boost. Could be a wastegate problem?

Here are a few others: Skinny tires Thinner oil in engine, trans, and diff A lot of ignition timing (35 degrees) during "low load" conditions Lean mixture A lot of overdrive to reduce rpms Headers and free flowing exhaust Don't use high volume oil pumps If you have a Holley carb, use a bigger spring in the vac secondary and lower numbered power valve. Roller cam Lighter feet

No wonder it takes you soon long to get to 14 psi, your label states you are only using 13 psi! LOL. Just kidding. What wastegate are you using? What have you done to the exhaust side of the turbo (turbine wheel stage, a/r housing, clipping, ect) What trim are you using with your T04E? How old is the turbo? Are the bearings in good shape? 4K is pretty bad, however I just recently switched from a straight T3 which gave full boost (12 psi) at 2800 rpm to a T04B-H3/T3 stage 3 which now gives full boost at 3500 rpms. And 2-3 psi at 2500, 5-6 psi at 3,000 and 12 psi at 3,500. But, I'm getting another 1,000 rpms of usable engine power on the top end with the T4/T3.

0.100 seconds in the 1/4 mile for every 100 lbs is the general rule. I'm not a car weight expert but I would think a 240sx weighs at least as much as a 280Z or 280ZX. 2300 lb cars are hard to make due to safety regs and comfort options. The 240 sx feels solid and well insolated and comes with power locks, windows, back seats, ect. Furthermore, in stock form, 240sx's have the same hp and performance as a 280Z so I think they would weigh the same. With that said, the 240Z should have a weight advantage of 300 to 400 lbs. But this is just a guess.

Yes, gauge accuracy could be the problem. I have two compression gages. On a recent compression test using one turbo engine and two gages, one gage read 110 and the other read 140.

You need a aftermarket efi system that you can program the fuel delivery and ignition curve based on throttle position, rpm, manifold pressure, engine temp, and manifold air temp. You already knew that answer.

good numbers! But I think your ignition timing is low. 28 to 30 degrees should be possible. I used 28 degrees on a T3 and 12 psi of boost running a very lean 14.7 a/f ratio with an spearco IC and made 235 hp. 12.1 seems too rich. I thought 12.7 was ideal for power. yes, the stock turbine could be hurting max HP. A stage three wheel would be helpful but will spool up 400-500 rpms later. And you will lose a little low end torque but gain another 1000 rpms. Extra injectors in the ic tube is a nice mod!

The head will work just fine on a NA engine. However, I wouldn't install a P90 or P79 head on a engine with dished pistons (75 to 80 L28). If you put that head on a dished piston engine then the compression will be 7.4:1 (stock turbo compression) and that will kill power over the entire rpm range. In one of my Z's (NA 78 280Z), I'm using a P90 head on a L28 block with flat top pistons which makes 8.8:1 cr (stock 81 to 83 cr). If you are using a round port exhaust manifold it might be a good idea to grind the end of the manifold ports to fit the gasket. Just grind the last 1/4 inch of the port. Should take just a few minutes.

That is a good question. I would think that the intake would flow much more when force feed as compared to vacuum feed. I bet the formula to estimate power added from boost over normally aspirated would apply. ((boost +14.7)/14.7)= force induction muliplier. So at 8 psi of boost..... (8+14.7)/14.7) = 1.5442 then 1.5442 x 200cfm = 309 cfm. Just a guess but it sounds resonable.

JTR V8 conversion manual says to expect mid 14's at 95 mph for a stock 350 (185 bhp). Mid 13's means the guy was most likely using headers and a vortex 350. Not a bad run for a stock 350 in a Z.

Go to NipponPower.com they sell ACT, Spec, and Center force for Z's. The SPEC kits come in 5 levels of performance which range in torque holding capacity of 395 ft lbs to 600 ft lbs.

I'm using the stock nissan 2+2 pressure plate and a 6 puck, Spec, ceramic, sprung hub, clutch (stage 3). 12 psi of boost and no problem with slippage so far. However, the chatter kind of sucks but the pedal is soft. Next time I will try the Spec Kevlar clutch (stage 2, chatter free) with the spec pressure plate.

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You can do that. But you will need a FMU to increase fuel pressure under boost conditions. Bell Engineering sells a pretty good one. You will need 50 or 60 psi of fuel pressure at 6 or 7 psi of boost. The stock fuel pump will not flow enough volume after 50 psi. So, use two stock pumps in series (one pump feeding the other pump) to get the flow you need. Then, 26 to 28 degrees of ignition timing is about all your engine will stand under boost. If you used a P90 or P79 head on your 78 block (dished pitions) then you can turn the boost up to 10 or 12 psi. This head/block combo will make the stock turbo compression ratio. I'm using all stock 76 efi on a turbo long block with two fuel pumps, FMU set to 80 psi of fuel at 12 psi of boost, spearco IC. I also reduced the amount of timing from the dist. by welding the advance slot just a little. I used 20 degrees initial timing with 28 total. 235 hp at the wheels, 13.7@ 106 mph, 3.90 gear, later model 5 spd, and 2+2 clutch. But, a FMU is not a good way to control fuel. It works but just barely. If I drive hard anound town, the car will get very bad mileage because the FMU is overly rich at low boost and low rpms. Sub 10 mpg is easy to get around town. Megasquirt or the like should be used as soon as possible.

Mr. Turbo, Thanks for the gear/rpm data. I didn't consider using 29" tires, but 29's would be better than 26's as long as they fit. However, I was kind of leaning to setting up my car so driving on the street would be possible and 26" radials would look more "normal". But, 29's on the track would be much better! Your rpms at the end of the track indicate your 29" tires are growing to 32 inch at speed! I didn't consider that much tire growth in my rpm calculations. Jack, FYI, circle track guys sell used 9" diff all the time. A friend of mine recently got a pretty good deal on one.

Why a 3.08 gear.....I should have said 3.10 or 3.00 gear. 3.08 is a chevy ratio not a ford. I guess once a chevyman, always a chevyman. anyway.... I hope to hit 145mph in the 1/4 mile with 16 to 18 pounds of boost on a 350 or 383 cid. And, a 3.08 gear with a 26" tall tire at 145 mph will be reving the engine at 5,800 rpm (in theory). However, there will be some slippage so 6,000 to 6,200 should be the rpms at the end of the track. 6,200 should be enough. My 350 now hits the traps now at 135 in 4th gear at 7200 and it seems like too much. Maybe under extreme conditions and a lot of racing fuel and more boost then 150+ mph could be possible (6,500 rpm). But 145 is the limit at the track for cars w/out parachutes. Plus a turbo engine would like to pull on a 3.08 automatic and this combo would also make for a easy driving street machine. LOL. In theroy...... A 320 hp small block with 17 psi of boost added will make enough hp to get a 2900 lb car to 145mph in the 1/4 mile (690 hp). Even at 12 psi, a 135+mph 1/4 mile would be possible. It all depends on the power potenial of "base engine" before boost and how well the turbo is matched to the engine. Sorry, for the long and twisted answer.