Pyro

Tony, A 1:1 rate fpr will keep the injector flow constant with boost by keeping the pressure difference across the injector constant. If the manifold pressure goes up and the efi system doesn't compensate by increasing the fuel pressure the same amount then the extra pressure at the tip of the injector has the same effect on flow as lowering fuel pressure. For example, a static fuel pressure of 25 psi would not flow into a manifold with 25 psi of boost. I'm not saying that more fuel is better, but if less fuel is desired then just turn down the pulse width and let the 1:1 fpr do it's job.

there is a simple speciality tool for the L series engine that uses the cam as a lever point to compress the spring. This also requires filling the cylinder with compressed air to keep the valves up. I have done many spring changes this way. Maybe some eos oil additive will do the job plus using a cam with both oiling systems (internal and external) would be extra insurance.

Expect to make 85% the power of a similar built L28, since the L24 is around 15% less displacement. A stock L24 makes around 115hp at the wheels. In theory, if you add 14.7 psi of boost, it will double the output to 230hp.

stock cam have very slow ramps and soft valve springs so their isn't nearly as much stress on the metal. High performance cams tend to lift the valve much more aggressively and therefore require much stronger valve springs. This creates a double wammy, quick lifts and heavy springs really wear out the rubbing metal parts. Plus the new datsun cores are softer and the aftermarket rockers are not as good which isn't helping. It's better to get a stock cam reground and stock rockers resurfaced and not too use a very aggressive lift rate like schneider cams This problem is also hitting the old v8 engines hard. People with flat tappet high performance cams are having huge problems especially with the newest flat tappet cam profiles that are overly aggressive in my opinion.

Chevron Delo 15W-40 is diesel engine oil. It has tons of zinc and phosphorous. (0.151% and 0.138%). The old engine oils we once had used around 0.12% to 0.15%, now they use 0.005%. Not a red herring, plenty of articles on high performance cam failures and oil anti-wear content (ZN and P). here is the oil spec sheet http://www.matweb.com/search/datasheet.aspx?matguid=8234601b8c6941e4bf8ba16e47da1b56

Almost looks like the cam was running off the lash pad. If too thin a lash pad was used, the wear pattern will run on the side of the pivot ball. If the lash pad was way too thin, it will run off the pad. FYI, a thicker lash pad moves the wear pattern towards the valve side of the rocker arm pad and also make the valve train quiet by reducing the slop at the lash pad/rocker tip interface. The cam doesn't look like it was a regrind, so most likely a "cwc" casting which typically only require 0.160" lash pads (stock are 0.120"). Yes, todays engine oil's have much less anti-wear additives. Need to use oils with high zinc content or use an oil additive that replaces the zinc. yes, the bearings take a beating when cams go flat like that. Most likely too late so plan on turning the crank and getting some new bearings. Try breaking in the new cam with stock valve springs and EOS oil additive. and use both oiling systems (spray bar and an internally oiled cam).

should have full boost by 3500 rpm with a stage 3 turbine. overly rich will delay boost. retarded ignition timing will delay boost. How much timing are you using? A leaky wastegate will delay boost. It would be nice to know what compressor you have.

What t04b turbo was it? h3, v1/v2, ect??? what was the boost difference between the two turbo's? do you feel it was the turbine (stock vs stage 3) or the compressor (B vs. E) that made the difference?

well, 80 mph isn't exactly a no load situation. I have seen the same situation (near 0"hg at 80 mph) in a number of L28 turbo's. If you aren't close to boosting at 80 mph with a stock turbine then I would check for a leaky wastegate are maybe retarded ignition timing or a rich fuel mixture.

a 3.90 gear with a late model 5 speed (more od) is about the same overall ratio as a 3.54 with a early model 5 spd, or a stock turbo manual setup (3.54 with T5). You need to consider the trans gear in the overal gear equation (not just the rear diff). 5th gear x diff gear= overall gear ratio I think it is weird that you guys don't have the same thing going on with the stock turbo. My friend also had near 0 inhg manifold vacuum at 80mph with his turbo L28. 80 mph is around 3,000 rpm and that rpm the stock turbo can easily make full boost under load so almost boosting at that point during a light load doesn't seem weird to me.

Yes, that is right, cr and boost depends on engine design. But knowing that BMW made that NA engine with only 9.3:1 cr, I would assume adding 11 psi to it would be way too much. FYI, USA rates fuel octane differently. Our 93 octane is equal to 98 over seas.

I think I have made this same response 5 or 6 times now......... This is 1 way to add a turbo to a stock 75. Buy this stuff. Items 1 to 4 can be found at your local junk yard for $100. 1) stock turbo exhaust manifold 2) stock turbo with wastegate, down pipe, and J-pipe 3) stock turbo oil pan, oil pick up tube in pan, and drain line from turbo 4) stock oil sender tee and oil feed line 5) Bell Engineering FMU ($225.00 new) Things you need to do. 1) Install all the turbo stuff (items 1 to 4 listed above) 2) lock out the mechanical advance in the distributor. This will require some disassembly to find the advance slots then fill them up with rtv and let dry. Set initial timing to 24 degrees. Continue using the vacuum advance. 3) relocate the pcv under the intake or put on a 90 degree fitting to clear the turbo compressor. 4) mount the FMU by the fuel filter in the return line. Set fuel pressure to 60 psi at 7 psi of boost (stock wastegate setting). 5) connect the down pipe to the 75 exhaust system. should use a 2-1/2" exhaust system. A completely stock 75 should run a mid 14 second 1/4 mile at 96 mph with the above setup. good luck. FYI, the fmu increases fuel pressure while on boost so you don't need to change fuel injectors. But you may want to install a msd efi fuel pump (90.00 from summit racing). I would recommend to upgrade to a megasquirt efi system first then add a turbo later. The fmu works pretty well up to 7 psi of boost but it is kind of a crude solution for fuel enrichment. Final comment, The stock 75 clutch (225mm) will not last long. You should upgrade to a 2+2 clutch (240mm).

I used this site to find a good compressor match. http://www.squirrelpf.com/turbocalc/ the T04B 60-1, or 62-1, or even a H-3 works ok. didn't check the gt35/40. I used 305hp, 3.5 liter, 12.5 a/f, 0.47 bsfc, 1.5 psi IC loss, 6500 redline, 6000 max power, 3500 max boost, 3000 min boost. 6.5 psi to make 305hp. Yes, a free flowing turbine is important especially with a non turbo cam. A stage 5 0.82 a/r is a good choice.

compression is too high to run 11 psi. think about running 5 or 6 psi max. A power band from 2500 to 6500 is going to be tough to get. 3500 to 6500 is more like it. that turbo you are looking at is too small. You need around a T04B-62-1 trim compressor or a T04B-H3 for a low boost, 6500 rpm 3.5 liter. The turbine selection is also very important. I would call a few turbo shops and get some recommendations. I would guess a T4 turbine would be required for a 3.5 liter or maybe a very opened up T3. What is the hp of a 3.5 liter 635? if it is making 200hp and 225ftlbs of torque with no boost then it should make 280hp and 315ftlb 0f torque with 6 psi of boost.

FYI, 1969 to 78 vette's tilt the top of the radiator towards the engine. It looks like hood vents should be used if the top of the radiator is tilted forward.

dart 200cc iron eagles with 64cc chambers and straight plugs. Get the heads with larger 1.470 valve springs. As a minimum, block hugger headers, 2-1/4 dual exhaust with dynomax super turbos mufflers and a x-over pipe should be used. Install a compcam 292H and a 3000 rpm stall converter. I hope the block has flat top pistons because you need 10:1 cr with this cam. If you have dished pistons then use a thinner head gasket (0.023") and a compcam 280H and a 2800 stall. With traction the 292H setup will run high 11's at 116 mph, the 280H setup will run low 12's at 112 mph. Then you can always drop another second and pick up 10 mph with a 125hp of N02.

give us your engine and cooling system details. might get better answers if we know what you have

Very nice! I quit racing mine because I got tired of breaking stock rear end parts. Then my wife had a few kids which put a stop to racing for awhile. If I ever find that guy that knocked up my wife, I'm going to kick his ass. hahahaha. Anyways, how much did it cost to do that? Did you install that yourself?? I was thinking maybe 1500.00 in parts???

You need to recirculate if you are using a metered air flow efi system. 1" is the most common size. Bosch makes a cheap plastic one that works ok ($25.00). I used a turboXS unit on my car (120.00). You need to weld on short tube pieces on the lines going into the TB and the line into the turbo intake. Also, the flow should go smoothly into the intake line (in the direction of the flow). A simple 90 degree Tee is not the best way to do it.

The turbo setup and cam should match. A low rpm boosting turbine is restrictive. And this restriction makes a lot of exhaust manifold pressure which doesn't like cams with valve overlap due to excessive reversion (exhaust flowing into the intake manifold). So, turbo cams typically have wide lobe separation to reduce the amount of overlap. However, free flowing turbines have much less restriction which lowers exhaust manifold pressure. And valve overlap is not a problem if the exhaust pressure is less than the intake pressure. But the free flowing turbines spool up much later. These turbines do well with normal NA cam prolifes. A stock L28 NA cam doesn't have that much more over lap than a stock turbo cam. It does have 8 more degrees of intake duration which is good for another 500 to 750 rpm of usable power. And using an aftermarket down pipe and bigger exhaust should help the stock turbine flow well enough to use a stock NA cam. I use a MSA stage 1 turbo cam. Has 260 intake, 250 exhaust, and 114 LSA. pulls hard to 6700 rpms. I use a stage 3 T3 turbine which doesn't hit full boost until 3500 rpms. If I had to do it all over again. I would use a NA cam (248/248 degrees) with a stock turbine and aftermarket down pipe. Then use a T04E-50 trim compressor.

A q-jet will need more than a jet change to run a lopey cam. Just get a holley 3310 750 cfm with vacuum secondarys. They are cheap, dependable, run well, and are easy to tune. forget the performer intake, you need the performer rpm intake heads will need to be machined to hold 1.470" springs and will need screw in studs and guide plates. You will be better off getting a set of dart iron eagles (64cc chambers, 200cc intake ports, straight plugs). They come with springs, retainers, screw in studs, and with a valve job. Plus they flow 40 more cfm right out of the box which translates to about 40 more hp. 3.90 gear, 3000 stall, and a compcam 292H would work nicely with 10.5 to 11:1 cr. will make power to 7,000 rpm. Make sure to use engine oil with lots of zinc or use an additive to regular oil.

Dynomax Bullets work great as a pre-muffler. Good choice. cheap too. flow like a straight pipe. I used a set on a Z V8 conversion and the difference was amazing. It went from a super loud droning sound (like riding in a sub woofer box) to almost the sound of a stock exhaust system.

A turbo engine requires a lot of fuel on boost. So bigger injectors must be used. And the problem with big injectors is their duty cycles needs to be very low at idle. And low impedance injectors have much better fuel control at low duty cycles, thus allowing a better idle. This is only an issue with boosted engine that require a wider range of fuel volume. I said the hy35 turbo compressor maps looks pretty good, but not as good as a t04e-50 trim (which is not a stock turbo). I also said that I wasn't sure how the hy35 turbine works with a L28. And since the turbine effects the how soon the turbo spools up, it is an important characteristic to know. But I'm pretty sure the stock wastegate will not bolt to it. What did it take to bolt the hy35 to the stock exhaust manifold, wastegate, and downpipe? The stock turbo engine falls off on power between 5000 and 5500 mainly because of it's small cam. Yes, the stock turbine restriction and the hot compressor doesn't help either. But I would guess that your power is falling off hard at 6000 rpm if you are using a stock cam. I had a stock turbo cam for a short time and it would rev to 6000 but not very well. Most dyno's I have seen peak at 5200 rpm when using a stock turbo cam regardless of turbo used.

Well, yes and no. Installing a stock wastegate and MSA down pipe on a T3 turbine will be very easy and good enough for 300hp. Installing an external wastegate would be better but gets expensive and complicated. And installing a hy35 turbo will also lead to some custom fab work. So to keep it simple and good enough for a high torque, low rpm street engine....then use a stock t3 turbine, stock wastegate, and msa down pipe. (2-1/2 down pipe is all you need). Save your money for a megasquirt efi system. And if you lower your goal to say, 250hp at the tires then you could get by with a completely stock turbo and save a bunch of money. 250hp at the wheels in a 240 still makes a very quick car.

Not just any t3/t4. You need a T04E with a 50 trim on a stock L28 T3 turbine. Makes a big difference. Yes, megasquirt II would be a good idea. Get it with low impedance drivers and ignition timing control. Yes, 7,000 rpm is very doable with a L28. However, you get around a 3000 rpm power band. So, if it makes power to 7K, then it will not make power until 4K. Power from 3K to 6K is better for the street, so set it up with that in mind. Sorry, no experience with HY35 turbos. The compressor maps seem pretty good for a L28, but not as good as a T04e-50 trim (IMO). The good thing is hy35's are cheap and easily found on ebay. Not sure how the exhaust turbine works with a L28, but I'm sure it will be harder to install as compared to using the stock turbine and waste-gate with a prefabbed msa down pipe.