Datsun 620 SR20 Turbo help!

[Kami04]

Sorry if this has already been discussed I dropped my SR20 into my 620 this past weekend and thankfully everything went smoothly with the mounts Redeye produces would heavily recommend him to anyone. I’m trying to figure out a turbo set up the plan I had did not fit. It was the ISR ram horn top mount manifold so I’m thinking I need to go bottom mount has anyone done this swap and stayed boosted? Any guidance is greatly appreciated!

[Wildcat Walker]

Your mileage may vary, welcome to the world of engine swaps. I stayed with the stock SR manifold and T25 on mine. Worked fine. Try something until it fits. 

Edited January 8 by Wildcat Walker

[Kami04]

15 hours ago, Wildcat Walker said:

Your mileage may vary, welcome to the world of engine swaps. I stayed with the stock SR manifold and T25 on mine. Worked fine. Try something until it fits. 

Damn I’m thinking about trying enjuku racings bottom mount turbo upgrade package 

[Stoffregen Motorsports]

On 1/3/2024 at 7:39 AM, Kami04 said:

Sorry if this has already been discussed I dropped my SR20 into my 620 this past weekend and thankfully everything went smoothly with the mounts Redeye produces would heavily recommend him to anyone. I’m trying to figure out a turbo set up the plan I had did not fit. It was the ISR ram horn top mount manifold so I’m thinking I need to go bottom mount has anyone done this swap and stayed boosted? Any guidance is greatly appreciated!

We just discussed this in another thread. The brake booster is one major problem. I would delete the brake booster.

[Wildcat Walker]

Do not delete the brake booster. I have driven many thousands of miles with an SR20DET swapped 620, with a booster, with a d21 disc brake swap. You definitely want all the braking performance you can get. Make the manifold and booster work together, it can be done. Don't sacrifice your safety. 

[IZRL]

Back when I had my 240 swap sr20. I had some issues with the original T25. My goal was to upgrade to the disco potato at some point but I couldn't afford all the other upgrades it would take to run that turbo. So I went with a used t28 off of an S14 engine. It wasn't a big upgrade but it was definitely enough to be noticeable. Plus it was the cheapest option at the time and it bolted right in without taking a grinder to the manifold or re-clocking the turbo. Who knows, this turbo might work with the limited space you have?

Edited January 11 by IZRL

[Stoffregen Motorsports]

1 hour ago, Wildcat Walker said:

Do not delete the brake booster. I have driven many thousands of miles with an SR20DET swapped 620, with a booster, with a d21 disc brake swap. You definitely want all the braking performance you can get. Make the manifold and booster work together, it can be done. Don't sacrifice your safety. 

We've been over this. Manual brakes are not "unsafe". They just require proper setup.

[Wildcat Walker]

28 minutes ago, Stoffregen Motorsports said:

We've been over this. Manual brakes are not "unsafe". They just require proper setup.

Sure, if you can get the same or better braking without a booster by retrofitting upgraded components. Intentionally reducing braking in order to fit parts that make the vehicle accelerate faster is not a good idea. 

[Icehouse]

2 hours ago, Wildcat Walker said:

Sure, if you can get the same or better braking without a booster by retrofitting upgraded components. Intentionally reducing braking in order to fit parts that make the vehicle accelerate faster is not a good idea. 

 

A booster is just helping you push the pedal.  Circle track racers unhook the booster when building "hornet" cars.  The booster makes the brakes lock up to easy.  Easy test.  unhook the booster in a test environment slam the brakes.  If you can lock them you haven't reduced any braking by removing the booster.  I like the feel of no booster.  To me especially for racing you can really modulate the brakes better.  

[datzenmike]

While I agree they act the same you don't want to use more foot pressure than necessary when just driving around and certainly not in stop and go. The booster just makes driving/braking easier and reduces fatigue. I'm all for easier.

[Wildcat Walker]

Actually the booster provides an additional force vector on the brake master. The line of action is the same as the input from the pedal, therefore they can be summed. This is why it is easier to achieve the same braking with less pedal input. For example, if with all your might you can apply 200lbs of pressure through the pedal assembly without the booster, and then suddenly you applied a vacuum to the booster, an additional force would be applied to the master equivalent to the pressure of the vacuum divided by the working area of the diaphragm.

 

Can you lock the wheels with or without the booster, probably. But how often are we locking the wheels while we are trying to slow down? Most of us aren't running stock tire sizes therefore the capable braking torque before lock up is higher. The booster will always provide more braking force at any given operator pedal input, assuming you don't install the check valve backwards like Redeye did. 

 

I never locked up my front wheels running the booster and D21 brakes and I regularly slowed down rapidly from high speeds.

[datzenmike]

The FSMs show a diagram and on the graph the difference is about a 50% increase in brake line pressure with the booster connected to a vacuum source. The 510 didn't have a booster but it's 2,200 pounds (and neither did the 1200) and probably no booster needed but cars after that were getting heavier. The later 610/710/620/B-210 and all after got boosters.

 

 

[Stoffregen Motorsports]

All I'm saying is that many performance builds do not include power brakes. If the pedal ratio is right, and the volume of the master and calipers is balanced, there is physically no need for a booster.

[Icehouse]

7 hours ago, Stoffregen Motorsports said:

All I'm saying is that many performance builds do not include power brakes. If the pedal ratio is right, and the volume of the master and calipers is balanced, there is physically no need for a booster.

 

I'd go one step further and say any smaller car is better off without a booster unless it has ABS.  Brake boosted car and an emergency stop and you are doomed!  Thus why ABS is required on all cars now.